explain xkcd - User contributions [en]

2101: Technical Analysis

2024-06-20T02:49:36Z

Capybarafan436: /* Explanation */

{{comic
| number = 2101
| date = January 21, 2019
| title = Technical Analysis
| image = technical_analysis.png
| titletext = "I [suspect] that we are throwing more and more of our resources, including the cream of our youth, into financial activities remote from the production of goods and services, into activities that generate high private rewards disproportionate to their social productivity. I suspect that the immense power of the computer is being harnessed to this 'paper economy', not to do the same transactions more economically but to balloon the quantity and variety of financial exchanges." --James Tobin, July 1984
}}

==Explanation==
There are two recognized methods to attempt to predict the stock market, each with its own pros and cons:

*{{w|Technical analysis}} is more appropriate for traders seeking to benefit off short-term fluctuations in stock prices, by attempting to look for trends, momentum, patterns etc. in the stock prices.
*{{w|Fundamental analysis}} is more appropriate for investors seeking to benefit off long-term fluctuations in stock prices, by attempting to guess future earnings based on some fundamental factor about the companies whose stock is traded. Investors can choose to look for good Price/Earnings ratio, the potential of a company to disrupt markets or open new markets, or other indications that a stock may be a solid investment.

[http://www.investopedia.com/terms/r/randomwalktheory.asp Random Walk theory] suggests that neither of these methods are particularly useful at predicting the future of the stock market.

The theoretical value of a stock is its {{w|net present value}}, which is the sum of all its future earnings, with earnings in the future discounted appropriately to account for the {{w|time value of money}}. Because these earnings are never fully predictable, traders may have different ideas about the true value of a stock, and buy the stock if they believe the currently offered prices are particularly low, or sell it when the prices are high.

Technical analysis, however, does not even attempt to understand the earnings of the stock, instead focusing on the shapes and patterns that result from traders making their moves. While there is a human behavioral component to stock trading, it is not clear that one can extract much information from the shapes of stock charts. To the extent it does work, a substantial part of its success may be simply an artifact of the herd behavior of traders who engage in technical analysis, a zero-sum game.

The comic displays a {{w|Candlestick chart|stock price chart}}, annotated with labels which purport to be technical analysis. These labels are nonsense from the perspective of technical analysis, but do accurately describe the graph itself: "{{w|allegro}}" (a musical term used to set the tempo at the beginning of a score), "{{w|prologue}}" (an introductory section of a play, book, or similar), "{{w|lumbar}} support" (the thing in a chair shaped to better support your back), "bathtub" (possibly a reference to the so-called "{{w|Bathtub curve}}"), "{{w|uptalk}}" (a speech pattern). One label celebrates that "these two points define a line! Promising signal." (In geometry, any two points define a line.)

The shape of the chart is similar to the exponential behavior of cryptocurrencies when they are successful, where price (positional height on the chart) roughly increases while volatility (height of the bars or candles themselves, and of the peaks and troughs, on the chart) does the same. Technical analysis used to be an esoteric domain held by well-paid stock analysts, but as cryptocurrency has spread, and as financial companies have made it easier for members of the public ("retail investors", as opposed to "institutional investors") to engage in investment trading, people from all walks of life have begun staring at charts like this.

{| class="wikitable"
|+Graph labels and possible meanings
|-
|{{w|Allegro_(music)|Allegro}}
|Tempo notation in music: played quickly and brightly (translation from Italian: cheerful, lively) - a series of very small changes in this region of the graph might suggest notes played quickly
|-
|Prologue
|A prologue is an introduction to a book or other work; this presumably refers to the initial period of minimal growth which is moving toward a much more active period
|-
|Decline
|Describes a negative trend
|-
|Doldrums
|A stagnant section of the graph with little movement
|-
|Spline
|A {{w|Spline (mathematics)|spline}} is a mathematical means of generating a smooth curve, referring to the smoothed curve shown here
|-
|{{w|Lumbar}} Support
|A cushion or other device that provides support to the lower part of the ''spine'', a play on the preceding ''spline''. "Support" is also used as a term in technical analysis to refer to a value that the stock price frequently approaches from above but does not pass through (until it does, which is taken as a sign that the price will fall further until it reaches the next support level).
|-
|Renewal
|Strong upward trend; also might suggest the growth of green bars, like greening up in the spring
|-
|Hmm!
|The three circles this label points to mark periods of growth that immediately preceded a decline. Ideally for someone performing a technical analysis, if such occurrences can be foreseen accurately it would be a major boon for the stockholder, as they could be tipped to sell it right away before the price drops and net a cash profit.
|-
|Hark! The cliffs!
|A long bar suggesting a steep cliff
|-
|Declination
|A term which sounds similar to decline, but actually refers to the angular distance of a point from one of the poles. The declination of magnetic north is used to correct the difference between true and magnetic north.
|-
|Inflection
|A point at which the slope of a graph changes from an increasing slope (getting steeper) to a decreasing slope (getting less steep).
|-
|Uptalk
|A pattern of speech in which each sentence ends with rising inflection? Like a question? A play on "uptick", and also on the second meaning of "inflection"
|-
|Bathtub
|Possibly a reference to the so-called "{{w|Bathtub curve}}", also, the shape is similar to that of a bathtub, and is drawn containing water.
|-
|These two points define a line! Promising signal.
|In geometry, any two points define a line; also looks somewhat like a communication line between two towers. It is tempting when looking at market charts to draw imaginary lines that connect the extrema and hope it means something about the future. The drawn line in this case also just so happens to ignore the many periods of decline marked under "Declination" -- in this case it did eventually recover, but later labels (such as "likely to continue forever" at the end) suggest that this is more likely a case where blind optimism just so happens to have been right for those two particular points (as opposed to the many more possible pairs of points where the line wouldn't be so positive).
|-
|Yikes
|This section of the chart refers to the actual use of a candlestick chart, which is to document the difference between the opening and closing value of a stock. A long red bar shows that a stock closed at a much lower value than it opened at, which would be disastrous for someone trading that stock. The section shows a bearish {{w|engulfing}}
|-
|Wrong!
|The circled pair of bars are the only pair in the whole graph where two red bars (negative growth) that large are next to each other -- larger red bars exist, but not next to another one of similar magnitude. Labeling it "wrong" suggests the analyst is choosing to ignore reality by throwing out actual past data rather than revise the theory being held.
|-
|If I add some lines here I can convince myself I'm doing something more than just seeing patterns in the graph of a random walk
|A {{w|random walk}} is a mathematical object that describes a path that consists of a succession of random steps. Randall is trying to convince himself that the patterns in the stock chart are more meaningful than just random data. The {{w|Random walk hypothesis|random walk hypothesis}} is a financial theory that states that stock prices evolve according to a random walk, thus short-term price changes are random and cannot be predicted from past history.

At this particular point, Randall has drawn a couple of lines that appear to act as an "envelope" around the stock price, converging towards the point where the price turns around and rises in the "Slope!" section. A technical analyst might say that such a convergence indicates that the price will turn around, but this annotation was added retroactively with the benefit of hindsight, like all of the annotations on this chart. If Randall had tried to make a similar envelope around the earlier sections ("Yikes" and "Wrong!"), before the "Slope!" had happened, he would have created a diverging (and descending) pattern, which he might have taken as a sign to sell and would have then missed the later rally of the stock price. More broadly, any two lines drawn over or around some part of the price chart must necessarily converge or diverge (the price would have to be perfectly periodic to produce parallel lines), so this "signal" is no better than a coin flip.
|-
|Slope!
|The {{w|slope}} of a graph is the ratio of the "vertical change" to the "horizontal change". A measure of slope on a financial chart can be used to predict possible specific returns or losses, or to analyze those from the past, but Randall simply prints the word in his chart annotation, with an exclamation point possibly indicating how exciting its value is, rather than labeling the actual numeric slope. This could also be a play on a second meaning of slope, meaning a rising or falling surface in general.
|-
|Could be an omen?
|This again makes reference to the financial meaning of the candlestick chart. The top of the small grey tick represents the highest value that the stock sold at over that day. The joke is that even though the stock did not grow appreciably, and actually sold at some point in the day for much lower, that it "could be an omen" that the value was rising.
|-
|Red + Green = Christmas
|Red and green are traditional colors for the {{w|Christmas}} holiday in the U.S. This could be a "sign" that the stock price is about to rise, as in a sort of Christmas present or bonus, or the [https://www.bloomberg.com/news/articles/2020-01-23/bitcoin-slumps-in-wake-of-chinese-new-year-slowdown-warning widely-held belief in the cryptocurrency community] that prices fall during {{w|Chinese New Year}} as Chinese holders of cryptocurrency sell off in preparation for their holiday expenses.
|-
|Likely to continue forever
|This is a mistaken opinion often held by buyers in a rising market. It's been rising so much, surely it's the best time to buy! We could make millions! Such times are generally followed by a sharp downturn resulting in significant losses, as can be seen historically farther back on the chart. Cryptocurrency communities have significant members who call themselves "holders" -- these people always trust that the price will eventually go up even higher, because it has recovered so many times in the past.
|}

The title text is a quote from {{w|James Tobin}} (from his 1984 paper [https://economicsociologydotorg.files.wordpress.com/2014/12/tobin-on-the-efficiency-of-the-financial-system.pdf ''On the efficiency of the financial system'']) that raises a question of very talented people building systems to make themselves a lot of money without actually accomplishing anything worth money. The quote was about the stock market and high speed traders in particular. It comments on the 'financialization' of the economy, where activities like speculation and abstracted financial products have become an increasingly large part of the economy, as opposed to investment in productive industry.

Interestingly, this comic appeared the day after [https://www.oxfamamerica.org/explore/stories/billionaire-wealth-grows-by-25-billion-a-day-while-poorest-wealth-falls/ Oxfam] reported that the world's 2,200 billionaires had added 12% to their wealth in 2018, while the 3.8 billion people comprising the poorest half of the world's population had lost 11%. Perhaps this prompted what appears to be Randall's jab at those whose business is merely making money.

==Transcript==
:[A series of red and green box-and-whisker plots form a line that starts in the bottom left corner of the image and wiggles up to the top right corner, with a series of peaks and troughs that resemble a typical stock market diagram. The diagram is annotated with lines, arrows and text.]

::[Title in top left corner]
::The basics of technical analysis

::[A roughly horizontal section with mostly green boxes:]
::Allegro

::[A horizontal bracket encompasses the next three sections]
::Prologue

::[Slope becomes slightly negative. Mostly red boxes, bordered with a black line above and below:]
::Decline

::[A roughly horizontal section with mostly green boxes, bordered with a black line above and below:]
::Doldrums

::[Line curves upwards with mostly green boxes, with a dashed black line below:]
::Spline

::[Three green boxes at minor peaks in the line are circled and indicated with arrows:]
::[Hmm!]

::[A section with slight positive slope and a mixture of red and green boxes, with a solid black line below:]
::Lumbar support

::[Slope increases. All green boxes, with a black line through the centre:]
::Renewal

::[A sharp upwards incline, with two large green boxes:]
::Hark! The cliffs!

::[Two black dots and a dashed black line connect two major peaks:]
::These two points define a line! Promising signal

::[Inside trough between two major peaks is a roughly drawn black triangle:]
::Bathtub

::[Slope becomes negative, mostly red boxes with a black line through the centre:]
::Declination

::[At the lowest point of the trough:]
::Inflection

::[Slope becomes positive, mostly green boxes with a black line through the centre:]
::Uptalk

::[Slight negative slope, with large error bars. Mixture of red and green boxes. One red box is marked with an arrow:]
::Yikes!

::[Negative slope, all red boxes. Gap between two central boxes is circled:]
::Wrong!

::[Line rises then falls. Mixture of red and green boxes with non-parallel dashed black lines above and below:]
::If I add some lines here I can convince myself I'm doing something more than just seeing patterns in a graph of a random walk.

::[Positive slope, all green boxes with a black line through the centre:]
::Slope!

::[One error bar on a green box is circled:]
::Could be an omen?

::[Arrow indicating peak:]
::Red + Green = Christmas!

::[Positive slope, all green boxes with a wiggly black arrow through the centre. A separate arrow points off the edge of the page:]
::Likely to continue forever

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Charts]]
[[Category:Christmas]] 
[[Category:Music]] 
[[Category:Comics featuring real people]] 
[[Category:Stock Market]]

2101: Technical Analysis

2024-06-20T02:48:34Z

Capybarafan436: /* Explanation */

{{comic
| number = 2101
| date = January 21, 2019
| title = Technical Analysis
| image = technical_analysis.png
| titletext = "I [suspect] that we are throwing more and more of our resources, including the cream of our youth, into financial activities remote from the production of goods and services, into activities that generate high private rewards disproportionate to their social productivity. I suspect that the immense power of the computer is being harnessed to this 'paper economy', not to do the same transactions more economically but to balloon the quantity and variety of financial exchanges." --James Tobin, July 1984
}}

==Explanation==
There are two recognized methods to attempt to predict the stock market, each with its own pros and cons:

*{{w|Technical analysis}} is more appropriate for traders seeking to benefit off short-term fluctuations in stock prices, by attempting to look for trends, momentum, patterns etc. in the stock prices.
*{{w|Fundamental analysis}} is more appropriate for investors seeking to benefit off long-term fluctuations in stock prices, by attempting to guess future earnings based on some fundamental factor about the companies whose stock is traded. Investors can choose to look for good Price/Earnings ratio, the potential of a company to disrupt markets or open new markets, or other indications that a stock may be a solid investment.

[http://www.investopedia.com/terms/r/randomwalktheory.asp Random Walk theory] suggests that neither of these methods are particularly useful at predicting the future of the stock market.

The theoretical value of a stock is its {{w|net present value}}, which is the sum of all its future earnings, with earnings in the future discounted appropriately to account for the {{w|time value of money}}. Because these earnings are never fully predictable, traders may have different ideas about the true value of a stock, and buy the stock if they believe the currently offered prices are particularly low, or sell it when the prices are high.

Technical analysis, however, does not even attempt to understand the earnings of the stock, instead focusing on the shapes and patterns that result from traders making their moves. While there is a human behavioral component to stock trading, it is not clear that one can extract much information from the shapes of stock charts. To the extent it does work, a substantial part of its success may be simply an artifact of the herd behavior of traders who engage in technical analysis, a zero-sum game.

The comic displays a {{w|Candlestick chart|stock price chart}}, annotated with labels which purport to be technical analysis. These labels are nonsense from the perspective of technical analysis, but do accurately describe the graph itself: "{{w|allegro}}" (a musical term used to set the tempo at the beginning of a score), "{{w|prologue}}" (an introductory section of a play, book, or similar), "{{w|lumbar}} support" (the thing in a chair shaped to better support your back), "bathtub" (possibly a reference to the so-called "{{w|Bathtub curve}}"), "{{w|uptalk}}" (a speech pattern). One label celebrates that "these two points define a line! Promising signal." (In geometry, any two points define a line.)

The shape of the chart is similar to the exponential behavior of cryptocurrencies when they are successful, where price (positional height on the chart) roughly increases while volatility (height of the bars or candles themselves, and of the peaks and troughs, on the chart) does the same. Technical analysis used to be an esoteric domain held by well-paid stock analysts, but as cryptocurrency has spread, and as financial companies have made it easier for members of the public ("retail investors", as opposed to "institutional investors") to engage in investment trading, people from all walks of life have begun staring at charts like this.

{| class="wikitable"
|+Graph labels and possible meanings
|-
|{{w|Allegro_(music)|Allegro}}
|Tempo notation in music: played quickly and brightly (translation from Italian: cheerful, lively) - a series of very small changes in this region of the graph might suggest notes played quickly
|-
|Prologue
|A prologue is an introduction to a book or other work; this presumably refers to the initial period of minimal growth which is moving toward a much more active period
|-
|Decline
|Describes a negative trend
|-
|Doldrums
|A stagnant section of the graph with little movement
|-
|Spline
|A {{w|Spline (mathematics)|spline}} is a mathematical means of generating a smooth curve, referring to the smoothed curve shown here
|-
|{{w|Lumbar}} Support
|A cushion or other device that provides support to the lower part of the ''spine'', a play on the preceding ''spline''. "Support" is also used as a term in technical analysis to refer to a value that the stock price frequently approaches from above but does not pass through (until it does, which is taken as a sign that the price will fall further until it reaches the next support level).
|-
|Renewal
|Strong upward trend; also might suggest the growth of green bars, like greening up in the spring
|-
|Hmm!
|The three circles this label points to mark periods of growth that immediately preceded a decline. Ideally for someone performing a technical analysis, if such occurrences can be foreseen accurately it would be a major boon for the stockholder, as they could be tipped to sell it right away before the price drops and net a cash profit.
|-
|Hark! The cliffs!
|A long bar suggesting a steep cliff
|-
|Declination
|A term which sounds similar to decline, but actually refers to the angular distance of a point from one of the poles. The declination of magnetic north is used to correct the difference between true and magnetic north.
|-
|Inflection
|A point at which the slope of a graph changes from an increasing slope (getting steeper) to a decreasing slope (getting less steep).
|-
|Uptalk
|A pattern of speech in which each sentence ends with rising inflection? Like a question? A play on "uptick", and also on the second meaning of "inflection"
|-
|Bathtub
|possibly a reference to the so-called "{{w|Bathtub curve}}", also, the shape is similar to that of a bathtub, and is drawn containing water.
|-
|These two points define a line! Promising signal.
|In geometry, any two points define a line; also looks somewhat like a communication line between two towers. It is tempting when looking at market charts to draw imaginary lines that connect the extrema and hope it means something about the future. The drawn line in this case also just so happens to ignore the many periods of decline marked under "Declination" -- in this case it did eventually recover, but later labels (such as "likely to continue forever" at the end) suggest that this is more likely a case where blind optimism just so happens to have been right for those two particular points (as opposed to the many more possible pairs of points where the line wouldn't be so positive).
|-
|Yikes
|This section of the chart refers to the actual use of a candlestick chart, which is to document the difference between the opening and closing value of a stock. A long red bar shows that a stock closed at a much lower value than it opened at, which would be disastrous for someone trading that stock. The section shows a bearish {{w|engulfing}}
|-
|Wrong!
|The circled pair of bars are the only pair in the whole graph where two red bars (negative growth) that large are next to each other -- larger red bars exist, but not next to another one of similar magnitude. Labeling it "wrong" suggests the analyst is choosing to ignore reality by throwing out actual past data rather than revise the theory being held.
|-
|If I add some lines here I can convince myself I'm doing something more than just seeing patterns in the graph of a random walk
|A {{w|random walk}} is a mathematical object that describes a path that consists of a succession of random steps. Randall is trying to convince himself that the patterns in the stock chart are more meaningful than just random data. The {{w|Random walk hypothesis|random walk hypothesis}} is a financial theory that states that stock prices evolve according to a random walk, thus short-term price changes are random and cannot be predicted from past history.

At this particular point, Randall has drawn a couple of lines that appear to act as an "envelope" around the stock price, converging towards the point where the price turns around and rises in the "Slope!" section. A technical analyst might say that such a convergence indicates that the price will turn around, but this annotation was added retroactively with the benefit of hindsight, like all of the annotations on this chart. If Randall had tried to make a similar envelope around the earlier sections ("Yikes" and "Wrong!"), before the "Slope!" had happened, he would have created a diverging (and descending) pattern, which he might have taken as a sign to sell and would have then missed the later rally of the stock price. More broadly, any two lines drawn over or around some part of the price chart must necessarily converge or diverge (the price would have to be perfectly periodic to produce parallel lines), so this "signal" is no better than a coin flip.
|-
|Slope!
|The {{w|slope}} of a graph is the ratio of the "vertical change" to the "horizontal change". A measure of slope on a financial chart can be used to predict possible specific returns or losses, or to analyze those from the past, but Randall simply prints the word in his chart annotation, with an exclamation point possibly indicating how exciting its value is, rather than labeling the actual numeric slope. This could also be a play on a second meaning of slope, meaning a rising or falling surface in general.
|-
|Could be an omen?
|This again makes reference to the financial meaning of the candlestick chart. The top of the small grey tick represents the highest value that the stock sold at over that day. The joke is that even though the stock did not grow appreciably, and actually sold at some point in the day for much lower, that it "could be an omen" that the value was rising.
|-
|Red + Green = Christmas
|Red and green are traditional colors for the {{w|Christmas}} holiday in the U.S. This could be a "sign" that the stock price is about to rise, as in a sort of Christmas present or bonus, or the [https://www.bloomberg.com/news/articles/2020-01-23/bitcoin-slumps-in-wake-of-chinese-new-year-slowdown-warning widely-held belief in the cryptocurrency community] that prices fall during {{w|Chinese New Year}} as Chinese holders of cryptocurrency sell off in preparation for their holiday expenses.
|-
|Likely to continue forever
|This is a mistaken opinion often held by buyers in a rising market. It's been rising so much, surely it's the best time to buy! We could make millions! Such times are generally followed by a sharp downturn resulting in significant losses, as can be seen historically farther back on the chart. Cryptocurrency communities have significant members who call themselves "holders" -- these people always trust that the price will eventually go up even higher, because it has recovered so many times in the past.
|}

The title text is a quote from {{w|James Tobin}} (from his 1984 paper [https://economicsociologydotorg.files.wordpress.com/2014/12/tobin-on-the-efficiency-of-the-financial-system.pdf ''On the efficiency of the financial system'']) that raises a question of very talented people building systems to make themselves a lot of money without actually accomplishing anything worth money. The quote was about the stock market and high speed traders in particular. It comments on the 'financialization' of the economy, where activities like speculation and abstracted financial products have become an increasingly large part of the economy, as opposed to investment in productive industry.

Interestingly, this comic appeared the day after [https://www.oxfamamerica.org/explore/stories/billionaire-wealth-grows-by-25-billion-a-day-while-poorest-wealth-falls/ Oxfam] reported that the world's 2,200 billionaires had added 12% to their wealth in 2018, while the 3.8 billion people comprising the poorest half of the world's population had lost 11%. Perhaps this prompted what appears to be Randall's jab at those whose business is merely making money.

==Transcript==
:[A series of red and green box-and-whisker plots form a line that starts in the bottom left corner of the image and wiggles up to the top right corner, with a series of peaks and troughs that resemble a typical stock market diagram. The diagram is annotated with lines, arrows and text.]

::[Title in top left corner]
::The basics of technical analysis

::[A roughly horizontal section with mostly green boxes:]
::Allegro

::[A horizontal bracket encompasses the next three sections]
::Prologue

::[Slope becomes slightly negative. Mostly red boxes, bordered with a black line above and below:]
::Decline

::[A roughly horizontal section with mostly green boxes, bordered with a black line above and below:]
::Doldrums

::[Line curves upwards with mostly green boxes, with a dashed black line below:]
::Spline

::[Three green boxes at minor peaks in the line are circled and indicated with arrows:]
::[Hmm!]

::[A section with slight positive slope and a mixture of red and green boxes, with a solid black line below:]
::Lumbar support

::[Slope increases. All green boxes, with a black line through the centre:]
::Renewal

::[A sharp upwards incline, with two large green boxes:]
::Hark! The cliffs!

::[Two black dots and a dashed black line connect two major peaks:]
::These two points define a line! Promising signal

::[Inside trough between two major peaks is a roughly drawn black triangle:]
::Bathtub

::[Slope becomes negative, mostly red boxes with a black line through the centre:]
::Declination

::[At the lowest point of the trough:]
::Inflection

::[Slope becomes positive, mostly green boxes with a black line through the centre:]
::Uptalk

::[Slight negative slope, with large error bars. Mixture of red and green boxes. One red box is marked with an arrow:]
::Yikes!

::[Negative slope, all red boxes. Gap between two central boxes is circled:]
::Wrong!

::[Line rises then falls. Mixture of red and green boxes with non-parallel dashed black lines above and below:]
::If I add some lines here I can convince myself I'm doing something more than just seeing patterns in a graph of a random walk.

::[Positive slope, all green boxes with a black line through the centre:]
::Slope!

::[One error bar on a green box is circled:]
::Could be an omen?

::[Arrow indicating peak:]
::Red + Green = Christmas!

::[Positive slope, all green boxes with a wiggly black arrow through the centre. A separate arrow points off the edge of the page:]
::Likely to continue forever

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Charts]]
[[Category:Christmas]] 
[[Category:Music]] 
[[Category:Comics featuring real people]] 
[[Category:Stock Market]]

2929: Good and Bad Ideas

2024-05-07T11:27:10Z

Capybarafan436: /* Explanation */

{{comic
| number = 2929
| date = May 6, 2024
| title = Good and Bad Ideas
| image = good_and_bad_ideas_2x.png
| imagesize = 595x522px
| noexpand = true
| titletext = While it seemed like a fun prank at the time, I realize my prank fire extinguishers full of leaded gasoline were a mistake.
}}

==Explanation==
{{incomplete|Created by a BLOOD FOR THE BLOOD GOD- Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This is a scatter plot comparing how good an idea sounds to how good the idea actually is. For example, leaded gasoline sounds like a good idea due to the anti-knocking effects, but is actually a bad idea due to lead toxicity. Fake prank fire extinguishers however sound bad and are bad as they can result in a dangerous situation in an emergency. Putting mold on infections sounds like a bad idea, but this could be referring to Penicillin, an antibiotic.

The title text combines leaded gasoline and a fake prank fire extinguisher into something that is worse than either. Not only is the fire extinguisher fake, it also releases flammable material onto the fire, and there is the additional lead toxicity.

{| class="wikitable"
|-
! Idea !! What it means !! How good it sounds !! How good it actually is !! Explanation
|-
|Leaded Gasoline||Adding {{w|Tetraethyllead|tetraethyl lead}} to gasoline to reduce noise and/or increase performance||++||---||Leaded gasoline was introduced in the early 1920s to eliminate engine knocking and greatly increase fuel efficiency and engine performance. Lead, however, is toxic. Burning the leaded gasoline in an engine releases the lead in the air. This is bad, and was known to be bad at the time, which is why there was an extensive PR campaign by oil companies to prove the alleged safety of the new product which, broadly speaking, succeeded up until the 1970s.
|-
|Bloodletting||Releasing "bad blood" from the veins||---||---||You need (most of) your blood.{{Citation needed}} Bloodletting has been performed as a medical procedure for at least 2000 years until it was considered pseudoscience from the 19th century, when the harmful effects became known. The idea was to withdraw blood to balance the body's "humors". Nowadays {{w|phlebotomy}} is only used therapeutically in a small number of cases, such as hemochromatosis (too much iron in the body).
|-
|{{w|Asbestos}}||Mineral which does not burn and is good insulation, isolation, and fire-retardant||+++||---||Asbestos was used extensively in buildings throughout most of the 20th century. Sadly the microscopic fibers which make up asbestos greatly increase the risk of cancer when inhaled.
|-
|Extension cords with prongs on both ends||allows easy connection between 2 female connectors||0 (neutral)||---||Prongs on both ends would make it easier to plug the extension cord in on either side. But once plugged into an outlet, the other end becomes a serious shock hazard.
|-
|Stair Kayaking||Riding down a flight of stairs in a {{w|kayak}}||--||---|| Stair kayaking is a stunt where a person positions a kayak at the top of a flight of stairs and then, using their paddle to push off, rides the kayak down the stairs. This poses significant easily foreseeable risks of injury or death, as well as being very bad for the kayak, which is designed to ride on water, not concrete.
|-
|Fake prank fire extinguishers||||---||---|| The idea of placing fake fire extinguishers as a prank, presumably so that a person who thinks they are grabbing a real fire extinguisher will instead find a decoy, sounds very dangerous and potentially life-threatening for many people, and it would, in fact, be highly dangerous. In the United States, (and presumably most countries), this would also be a felony in most, if not all, jurisdictions. An example of a similar situation, although not intended as a prank, can be found [https://twitter.com/ThatSamWinkler/status/1657154071051239424 here].
The title text expands this idea by having the prank fire extinguishers filled with (leaded) gasoline. This is literally adding fuel to the fire.
|-
|Always saying what you think||...regardless of the feelings of others or other considerations||++||--||Openness and honesty are seen as positive character traits in people. However, taken to the extreme of ''always'' telling people what you think about them, they can lead to awkward or unpleasant situations. It may harm your relationship with the other person if they don't like what you think, or they may reply without concern for ''your'' feelings or other considerations. Keeping negative thoughts to yourself or telling "white lies" can be considered a better alternative in some situations.
|-
|Replying to spammers||Clicking on the "Reply" button from spam mails and writing (and sending) a reply (or worse, clicking on the links in these mails)||--||--||At best, you confirm your email address and identify yourself as someone likely to respond to such unsolicited messages, and so encourage the spammers to deluge you with even more messages. At worst, the spammer may use your correspondence to extract sensitive information about you, or make you victim to a scam.
|-
|Solar cars||Having {{w|Solar panel|solar panels}} on the car's surface (mostly hood and roof) for power generation||+++||-||Cars require large amounts of energy in short periods of time and portable solar panels generally do not produce enough, nor are they as efficient as fixed installations on the power grid.
There are competitions for solar powered cars, though, like the {{w|World Solar Challenge}}.
|-
|Heelies||{{w|Heelys}} are shoes with a inline skate wheel embedded in the sole, at the heel. ||+||-||Heelys allow the wearer (usually children) to shift between normal walking and rolling like a roller skate. This sounds like fun but has led to numerous injuries.{{Actual citation needed}}
|-
|Prequels||A work of fiction (mostly movie) telling the "story before the story" of another work of fiction.||+++||-||More of a good story sounds great on the surface, but the constraints of a prequel's ending needing to create the starting conditions of the original work often precludes organic development and causes contrived plots.
|-
|Transition Lenses||A brand name for {{w|Photochromic_lens|photochromic lenses}} in glasses, which get darker (like sunglasses) in bright light.||+||-||Photochromic lenses are clear lenses that darken when exposed to UV light, then turn clear again when the exposure is removed. The advantage is that wearers of glasses don't need to buy separate (prescription) sunglasses. However, the process is relatively slow (about a minute) so not so useful when there is a quick succession of shade and bright light, perhaps in a forest or when driving. Also, car windscreen filter out UV light to some degree, which prevents the glasses from darkening as required. Finally, the process is temperature dependent, so in hot weather the glasses don't become as dark and in cold weather they might stay dark for too long.
|-
|Cutting pizza in squares||Cutting (a presumably round) pizza in squares||-||-||Most people cut pizza into wedges and hold it by the crust. Cutting it into squares allows for more pieces to be shared, but pieces near the center will have no crust to hold it by, getting cheese and sauce all over your fingers. There will also be lots of leftover tiny pieces. While hardly a disaster like the other items in its quadrant, square pizza pieces are just not very useful and rather inefficient. Cutting a rectangular pizza into squares might not suffer from the problems above, but, unless the pizza itself is square and cut only into four squares, some people will end up with a higher crust-to-topping ratio than others.
|-
|{{w|Project Orion (nuclear propulsion)|Project Orion}}||Study by the U.S. government looking into nuclear pulse propulsion for spacecraft.||---||-||Using repeated nuclear explosions to generate motion sounds bad for both the spacecraft and everything else, especially with a ground launch, but there are ways to address a lot of the concerns, so it isn't as bad as it sounds. Project Orion's theorized specific impulse and thrust would also be far higher than anything chemical rockets can accomplish. The efficiency of Project Orion is extremely low, however.
|-
|Soup||Soup||0 (neutral)||0 (neutral)||Soup is probably one of the oldest foods created by prehistoric cooks. Many people enjoy it, though some consider many soups somewhat lacking as a meal on their own, or bland.
|-
|Combo washer dryers||A device which combines washing machine and laundry dryer into one device||+++||+||Better at space efficiency, but worse at each task than separate devices.
|-
|Cutting sandwiches diagonally||Cutting sandwiches diagonally||+||+||Generally regarded{{Actual citation needed}} as the structurally superior way to slice a sandwich, providing better support in the hand and fewer all-crust bites. Required in the assembly of a club sandwich, where the diagonal components are stacked again.
|-
|{{w|Diverging diamond interchange|Diverging diamond interchanges}}||Road junction where the two (sets of) lanes cross over to switch sides (so if you normally drive on the right, now you drive on the left), then switch back to normal after the junction||-||+||Highway engineers believe the shape improves safety and traffic flow through the interchange because switching to the other side facilitates merging to and from the other road in the junction. However the shape appears to be insanity to an unfamiliar driver.
|-
|Toasting sandwiches||Making a sandwich first and then cooking it, as in a dedicated {{w|Pie_iron|sandwich toaster}}, a {{w|toaster oven|toaster oven}} or frying pan, or under a grill.||++||++||The grilled cheese sandwich is a familiar form to most people, and many other sandwiches are improved by toasting as a final step. Others, such as the {{w|western sandwich|Western}} or {{w|club sandwich|club}} are prepared using toast. The {{w|peanut butter, banana and bacon sandwich|Elvis}} is a specific case of a sandwich that normally wouldn't be toasted, but is improved by it - peanut butter, bacon, banana, and jelly, with the assembly lightly fried.
|-
|Crumple zones||Designated areas of a car that crumple in case of a crash... ||--||++||...to absorb the energy of the crash to prevent damage to the passengers
|-
|Sliced bread||Bread, sliced by the baker before packaging for sale||+++||++||It's far more convenient for making sandwiches or toast, but unfortunately pre-sliced bread will go stale faster and some applications may be better off thicker or thinner than the slices provided. Sliced bread is often used as a comparator for how good something is in the phrase 'the best thing since sliced bread'.
|-
|Pizza||Flat, though usually leavened, bread with tomato sauce, cheese, and often vegetables or preserved meats||++||++||Pizza is a widely popular dish throughout much of the world, uncontroversial {{w|Anchovies_as_food|except}} {{w|Pineapple|certain}} [https://www.taste.com.au/recipes/nutty-choc-pizza-fresh-berries/2c0220a4-8463-45ff-b2ba-ac7e5012a006 toppings].
|-
|Eating citrus fruit while at sea||||0 (neutral)||+++||The vitamin C present in some citrus fruits prevents one from developing {{w|Scurvy|scurvy}}.
|-
|Putting mold on infections||Seemingly a reference to ancient practice of pressing moldy bread against infected wounds||---||++||While this sounds like a good way to get a fungal infection, with the correct mold this is a primitive antibiotic, and led to the discovery of penicillin.
|-
|Wheels on luggage||Some luggage bags have small wheels inset on their frame and a carrying handle.||+++||+++||A relatively simple fitting for rigid or semi-rigid luggage that substantially eases its transport over long distances on flat surfaces such as travel terminals.
|-
|Heat pumps||Refrigeration (or air conditioning) technology operated in reverse to heat an area instead.||++||+++||Because refrigeration is a very efficient way to move heat (as long as the cold side's temperature is high enough) this is often far more energetically efficient than directly heating a space. Reversible heat pumps also exist which can take care of both temperature needs in some climates.
|-
|Laser eye surgery||Surgical techniques using lasers for precision cutting in the eyeball.||-||+++||This technology has substantially improved the eyesight of millions of people worldwide by allowing treatment of eye problems otherwise only corrected by lenses, or entirely untreatable. Randall has previously commented on laser eye surgery, amongst other ideas both good and bad, in [[1681: Laser Products]].
|-
|Fecal transplants||Transfer of gut microbiome of healthy person to sterilised gut of ill person.||---||+++||The gut microbiome is a collection of bacteria that lives in our guts. It can influence our health. It is responsible for last stages of digesting our food. It can also produce neurotransmitters that are carried by blood to our brain influencing our behaviour. A healthy microbiome can be destroyed by bad eating habits, unhealthy lifestyle, infections or antibiotics. The important part is a composition of different species of bacteria that compromise the biome. Sometimes it may be necessary to completely sterilise the gut and then take a sample of a healthy biome from another person. A sample is enough as the bacteria will multiply. As long as the patient eats correctly, the microbiome after transplant should develop correctly.

It sounds bad because we tend to think of our feces as something gross, to be discarded. It is called fecal transplant as our feces contain about 50% of gut bacteria, but nowadays the sample usually takes the form of a coated pill that is applied rectally.
|-
|}

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

{{comic discussion}}
[[Category:Charts]]

2884: Log Alignment

2024-01-22T22:29:19Z

Capybarafan436: grammar

{{comic
| number = 2884
| date = January 22, 2024
| title = Log Alignment
| image = log_alignment_2x.png
| imagesize = 351x312px
| noexpand = true
| titletext = A video can have a log scale that's misaligned with both the time AND space axes.
}}

==Explanation==
{{incomplete|Created by a BENDY LOG - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This comic jokes about how there isn't a rule in math that doesn't let you misalign log scale and graph axes. Therefore, the person who drew the graph in the comic decided to make it distorted. According to that person, this graph is still valid.

The title text further reinforces the concept of misalignment by stating that the time axis at the bottom of a video can be misaligned with the video itself and a log scale in that video.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Distorted bar graph on top of gray log scale lines in the background that are slightly tilted, with the lower ends on the left]

:[Caption below the panel:]
:There's actually no rule in math that says your log scales have to be aligned with your graph axes.

{{comic discussion}}

[[Category:Math]]
[[Category:Bar charts]]

977: Map Projections

2024-01-03T20:41:50Z

Capybarafan436: /* Explanation */ Added a link to an animation of the comic.

{{comic
| number = 977
| date = November 14, 2011
| title = Map Projections
| before = [[#Explanation|↓ Skip to explanation ↓]]
| image = map_projections.png
| titletext = What's that? You think I don't like the Peters map because I'm uncomfortable with having my cultural assumptions challenged? Are you sure you're not... ::puts on sunglasses:: ...projecting?
}}
{{TOC}}
==Explanation==
{{w|Map projection}}, or how to represent the spherical Earth surface onto a flat support (paper, screen...) to have a usable map, is a long-time issue with very practical aspects (navigation, geographical shapes and masses visualization, etc.) as well as very scientific/mathematical ones, involving geometry or even abstract algebra among other things. There is no universal solution to this problem: Any 2D map projection will always distort in a way the spherical reality. Many projections have been proposed in various contexts, each intending to minimize distortions for specific uses (for nautical navigation, for aerial navigation, for landmass size comparisons, etc.) but having drawbacks from other points of view. Some of them are more frequently used than others in mass media and therefore more well-known than others, some are purely historical and now deprecated, some are very obscure, etc.

[[Randall]] suggests here the idea that someone's "favorite" map projection can reveal aspects of their personality, then goes through a series of them to show what they can mean.

He may actually believe that all map projections are in a way bad. This could be inferred from the fact that he much later began publishing a series of [[:Category:Bad Map Projections|Bad Map Projections]].

An animated version of this comic, showing how the projections look when they are rotated, was uploaded [https://www.youtube.com/watch?v=7O2CBgWshiM here.]
===Mercator===
[[File:MercatorProjection.jpg|frame|The Mercator projection]]
The {{w|Mercator projection}} was introduced by Flemish cartographer Gerardus Mercator in 1569. The main purpose of this map is to preserve compass bearings; for example 13 degrees east of north will be 13 degrees clockwise from the ray pointing toward the top of the map, at every point. A mathematical consequence is the mapping is conformal, i.e. if two roads meet at a certain angle on the surface of the Earth, they will meet at that same angle on the map. It also follows that at every point the vertical and horizontal scales are the same, so locally i.e. considering only a small part of the map, geographical features (shapes, angles) are well represented, which helps a lot in recognizing them on-the-field, or for local navigation in that small part only. For this reason, that projection (or a close variant) is used in several online mapping services (such as Google Maps), which means that it is frequently encountered by the general public. A straight line on the map corresponds to a course of constant bearing (direction), which was very useful for nautical navigation in the past (and thus made that projection very well-known).

However, from a global point of view, this projection is radically incorrect in how it shows the size of landmasses (for instance, Antarctica and Greenland seem gigantic), and furthermore, it always excludes a small region around each pole (otherwise the map would be of infinite height), so it doesn't provide a complete solution for the problem of map projection. The comic implies that people who like that projection aren't very interested with map issues, and typically use what they are offered without thinking much about it.

{{clear}}

===Van der Grinten===
[[File:VanDerGrintenProjection.jpg|frame|The Van der Grinten projection]]
The {{w|Van der Grinten projection}} is not much better than the Mercator. It was adopted by {{w|National Geographic}} in 1922 and was used until they updated to the Robinson projection in 1988.

The Van der Grinten projection is circular as opposed to the Mercator projection. The fictional person believes a circular map is more fitting to the real Earth's three-dimensional spherical nature because both are round. This belief fails to recognize that a two-dimensional circle has very little in common with the surface of a sphere, and thus this projection still causes a vast distortion of space and area. Because of this, Randall implies the Van der Grinten enthusiast to be optimistic and childishly simple-minded (e.g. "you like circles").

{{clear}}

===Robinson===
[[File:RobinsonProjection.jpg|frame|The Robinson projection]]
The {{w|Robinson projection}} was developed by {{w|Arthur H. Robinson}} as a map that was supposed to look nice and is often used for classroom maps. National Geographic switched to this projection in 1988, and used it for ten years, switching to the {{w|Winkel tripel projection|Winkel-Tripel}} in 1998.

{{w|The Beatles}} was a rock band that enjoyed great commercial success in the 1960s, and are widely considered the best act ever in the genre of popular music. The Beatles, coffee, and running shoes are all things that are very commonly enjoyed and largely uncontroversial, as well as being comforting. Liking these specific things suggests an ordinary, easygoing lifestyle paralleled by the projection.

{{clear}}

===Dymaxion===
[[File:DymaxionProjection.jpg|frame|The Dymaxion projection]]
Also called the Fuller Map, the {{w|Dymaxion map}} takes a sphere and projects it onto an icosahedron, that is a polyhedron with 20 triangular faces. It is far easier to unwrap an icosahedron than it is to unwrap a sphere into a 2D object and has very little skewing of the poles. {{w|Buckminster Fuller}} was an eccentric futurist who believed, for example, that world maps should allow no conception of "up" or "down". He was therefore more than happy to defy people's expectations about maps in the pursuit of mathematical accuracy.

Randall associates the projection to geek subculture and niche markets:
*{{w|Isaac Asimov}} was an American science-fiction writer, who (as well as publishing many textbooks) is considered the father of the modern concept of robots. He invented the {{w|Three Laws of Robotics}}. He also worked on more than 500 books throughout his career.
*{{w|XML}} is the eXtensible Markup Language. It is used to represent data in a format that machines can read and understand, as well as being human-readable. In practice, XML is cumbersome to read.
*{{w|Vibram FiveFingers|Toed shoes}} are a [[1065: Shoes|favorite]] of Randall's to pick on. In society they are seen as a {{w|geek}} clothing item.
*Brought to the world by {{w|Dean Kamen}}, the {{w|Segway PT}} was supposed to be a device that changed the way cities were built. In practice, it had the same problems as other novel personal transporters, such as the {{w|Sinclair C5}} many years earlier. Small, powered vehicles didn't fit neatly into the existing infrastructure for cars, bikes or pedestrians; using them on roads or sidewalks could be unsafe, illegal or both. Early versions of the Segway also cost more than a used car, such that they were never widespread enough to provoke legal or infrastructure changes. The devices found a small niche among law enforcement, mall/airport security and tour operators, rather than private owners. The former owner of {{w|Segway Inc.}}, the late {{w|Jimi Heselden}}, accidentally rode his Segway off a cliff in 2010. Ninebot, then owner of the Segway brand, announced in 2020 that the flagship 2-wheeled self-balancing vehicle would be discontinued.
*At the time of comic release, 3D goggles, nowadays widely known as {{w|Virtual reality headset|VR headsets}}, were considered a gimmick at best. The original idea is as old as 3D graphics, but it never really took off until mid-2010s. Earlier products were very unwieldy and offered poor graphics quality, so no one took this technology seriously.
*{{w|Dvorak Simplified Keyboard|Dvorak}} is an alternate keyboard layout to {{w|QWERTY}}. According to legend, QWERTY was invented to help keep manual typewriters from jamming (by placing the most used keys far from each other) but Dr. {{w|August Dvorak}} performed many studies and found the mathematically optimal keyboard layout to reduce finger travel for right handed typists. While some claim Dvorak is technically better than QWERTY, QWERTY had become the standard. Most keyboards were laid out in QWERTY format, but a lot of software exists to remap the keys to DVORAK for those interested in typing faster. Retraining the brain to use Dvorak takes perhaps a week. It has become a [[:Category:Dvorak|recurrent theme]] on xkcd.

{{clear}}

===Winkel-Tripel===
[[File:Winkel-TripelProjection.jpg|frame|The Winkel Tripel projection]]
Proposed by Oswald Winkel in 1921, the {{w|Winkel tripel projection}} tried to reduce a set of three (German: Tripel) main problems with map projections: area, direction, and distance. The {{w|Kavrayskiy VII projection|Kavrayskiy projection}} is very similar to the Winkel Tripel and was used by the USSR, but very few in the Western world know of it.

The comic links this projection to {{w|hipster}} subculture. The hipster stereotype is to avoid conforming to mainstream fashions. "Post-" refers to a variety of musical genres such as {{w|post-punk}}, {{w|post-grunge}}, {{w|post-minimalism}}, {{w|post-rock}}, etc. that branch off of other genres, and are generally considered less accessible than the genres that spawned them. Liking a genre just called "post-" implies that the listener prefers music that is less mainstream, and may have that as the only criterion for listening.

;Trivia
*In German "Winkel-Tripel-Projektion" means Winkel's triple projection, and therefore the hyphen shouldn't be there: "Winkel Tripel" or "Winkel tripel".
*This projection was later used in [[2242: Ground vs Air]].
{{clear}}

===Goode Homolosine===
[[File:GoodeHomolosineProjection.jpg|frame|The Goode Homolosine projection]]
The {{w|Goode homolosine projection}} takes a different approach to skewing a sphere into a roughly circular surface. An orange peel can be taken from an orange and flattened with fair success; this is roughly the procedure that {{w|John Paule Goode}} followed in creating this projection. Randall is suggesting that people who like this map also prefer relatively easy solutions to other things in life, despite those solutions having nuanced problems that are more difficult to address.

People often make arguments that if normal people ran the United States, then the US wouldn't be in the trouble it is. This is from the belief that career politicians are simply out to make money and will only act in the interest of their constituency when their continued easy life is threatened (usually around election time). While some form of this view is very common and probably pretty much correct, Randall is saying that someone who likes this map may take this to extremes.

Airline food is another, much maligned, problem. How do you store enough food to feed people on long airplane trips? What kind of food can be served in an enclosed, low-air-pressure environment? The common solution is to use some kind of prepackaged, reheated meal. Randall is saying that the people in favor of the Goode Homolosine wonder why the airlines don't simply order meals from the restaurants in the airport, store that food, and serve it, rather than using bland reheated food. However, this seemingly-obvious solution ignores how being in an airplane dulls your sense of taste. Airplane food is actually over seasoned for eating on the ground, meaning that if airlines switched to restaurant food it would probably taste even blander. There would also be issues with acquiring special meals (for example, vegetarian, Kosher, and Halal meals), especially if suitable restaurants were not in close range to the airport.

Older cars burned oil like mad fiends, and oil back then would become corrosive to the innards of an engine, so oil had to be changed often. But, with the introduction of synthetic motor oil and better designed engines, new cars only need their oil changed about every 10,000 to 15,000 miles. A common conspiracy theory is that modern automobile oil manufacturers still recommend that car owners change their oil every 3,000-5,000 miles to "drum" up more business, even though that frequency is unnecessary.

All of these references suggest that people who like the Goode Homolosine projection are fans of simple solutions to problems. However, while the solutions appear to be an easy, common-sense solutions, they all rely on over-simplifying the problem, and ignoring any problems introduced by the solution itself. For instance: the restaurants might have trouble making enough food for the whole plane, and it could get cold before being served; the air conditions [https://www.nbcnews.com/health/one-reason-airline-food-so-bad-your-own-tastebuds-6C10823522 aboard planes] can affect taste, so airlines say they optimize for this; there is no such thing as a "normal" person, and if there were, they would have less political experience than politicians, while remaining subject to the same pressures and problems with the larger political system; and the Goode Homolosine projection, while mostly resembling a flattened orange peel as suggested by the earlier analogy, does indeed cut down on distortion, but also has serious problems of its own, such as leaving huge gaps of nothingness between the continents, making distances across the oceans difficult to visualize, and splitting Greenland in half.

{{clear}}

===Hobo–Dyer===
[[File:Hobo-DyerProjection.jpg|frame|The Hobo–Dyer projection]]
The {{w|Hobo–Dyer projection}} was commissioned by Bob Abramms and Howard Bronstein and was drafted by Mick Dyer in 2002. It is a modified {{w|Behrmann projection}}. The goal was to be a more visually pleasing version of the Gall–Peters.

As is discussed in the Gall–Peters explanation, the Gall–Peters was developed to be equal area, so that historically colonised and economically disadvantaged areas nearer the equator are not diminished in area by the map projection, while global north areas are generally enlarged.

Randall associates the Hobo–Dyer projection to "crunchy granola" — a stereotype associated with vegetarianism, environmental activism, anti-war activism, liberal political leanings, and some traces of {{w|hippie}} culture.

With feminism becoming mainstream and non-binary genders being more widely accepted, some have begun to invent gender-neutral pronouns so that when referring to a person whose gender is not known they cannot be offended by being referred to by the wrong pronouns. In {{w|Middle English}} 'they' and 'their' were {{w|Singular they|accepted genderless pronouns that could replace 'he', 'she'}} as well as be used to represent a crowd, but this usage is considered by some to be grammatically incorrect because of the plural/singular debate ([https://www.merriam-webster.com/video/the-awkward-case-of-his-or-her stupid Victorian Grammarians!]). There have been {{w|gender-neutral pronoun#Invented pronouns|many attempts at popularizing invented gender-neutral pronouns}} and they are beginning to achieve some degree of success in the mainstream.

{{clear}}

===Plate Carrée===
[[File:PlateCarreeProjection.jpg|frame|The Plate Carrée projection]]
Also known as the {{w|Equirectangular projection}}, it has apparently been in use since approximately 100 AD. The benefit of this projection is that latitude and longitude can be used as x,y coordinates. This makes it especially easy for computers to graph data on top of it.

According to the comic, the projection appeals to people who find much beauty in simplicity.

{{clear}}

===A Globe!===
[[File:GlobeProjection.jpg|frame|The Globe "projection"]]
In any good discussion there has to be at least one smart-ass.{{Citation needed}} This is a comic about map projections, that is, the science of taking a sphere and flattening it into 2 dimensions. The smart-ass believes that we shouldn't even try: a sphere is, tautologically, the perfect representation of a sphere.

To quote ''{{w|The Princess Bride}}'': "Yes, you're very smart. Shut up."

A globe is the "map projection" used by {{w|Google Earth}} when zoomed out.

{{clear}}

===Waterman butterfly===
[[File:WatermanButterflyProjection.jpg|frame|The Waterman Butterfly projection]]
Similar to the Dymaxion, the {{w|Waterman butterfly projection}} turns a sphere into an octahedron, and then unfolds the net of the octahedron, which was devised by mathematician {{w|Waterman polyhedron|Steve Waterman}} based upon the work of {{w|Bernard J.S. Cahill}}.

Bernard Cahill published a [https://www.genekeyes.com/B.J.S._CAHILL_RESOURCE.html butterfly map] in 1909. Steve Waterman probably has the only extant "ready to go" map following the same general principles, though Gene Keys may not be far behind. Waterman has a poem with graphics in a similar vein to this xkcd comic that is worth reading.[https://web.archive.org/web/20120118095915/https://watermanpolyhedron.com/worldmap.html]

[https://www.degruyter.com/downloadpdf/j/pcr.2016.48.issue-4/pcr-2016-0014/pcr-2016-0014.pdf Polyhedral projections] like Cahill, Dymaxion or Waterman typically offer better accuracy of size, shape and area than flat projections, at the expense of compass directionality, connectedness, and other complications.

The joke is that the person responding deeply understands map projections; anyone who knows of this projection is a person that Randall would like to get to know.

{{clear}}

===Peirce quincuncial===
[[File:PeirceQuincuncialProjection.jpg|frame|The Peirce Quincuncial projection]]
The {{w|Peirce quincuncial projection}} was devised by {{w|Charles Sanders Peirce}} in 1879 and uses {{w|complex analysis}} to make a {{w|conformal mapping}} of the Earth, that conforms except for four points which would make up the midpoints of sides and lie on equator (the equator is represented by a square and the corners connect the sides in the middle.)

{{w|Inception}} was a 2010 movie about {{w|meta}} {{w|lucid dream}}ing. It has a complex story that is difficult to follow and leaves the viewer with many questions at the end, and almost always needs to be watched multiple times to be understood.

The human brain is not well developed to deal with oddly obvious things. One example is that everyone has a skeleton, but everyone is surprised to see a part of their body represented by an X-ray. Another is the fascinating complexity of the human hand, a machine which is amazingly complex, driven by a complex interplay of electrical and chemical signals; yet is the size of the hand and so useful. A fascination with or fixation on {{tvtropes|ContemplatingYourHands|such thoughts}} is often associated with an altered state of mind brought on by marijuana consumption. Therefore, Randall may be implying that this map would appeal to stoners.

{{clear}}

===Gall–Peters===
[[File:Gall-PetersProjection.jpg|frame|The Gall–Peters projection]]
The {{w|Gall–Peters projection}} is mired in controversy, surprisingly for a map. {{w|James Gall}}, a 19th-century clergyman, presented this projection in 1855 before the {{w|British Association for the Advancement of Science}}. In 1967, the filmmaker {{w|Arno Peters}} created the same projection and presented it to the world as a "new invention" that put poorer, less powerful countries into their rightful proportions, (as opposed to the Mercator) during the US civil rights movement, when society was very concerned about social justice. Peters played the marketing game and got quite a few followers of his map by saying it had "absolute angle conformality," "no extreme distortions of form," and was "totally distance-factual". These claims were in fact false. The Mercator projection distorts size in favor of shape, and Gall-Peters distorts shape in favor of size, being especially inaccurate at the equator and the poles.

Anyone who loves such a politically charged map that has become popular by way of marketing stunts and false claims, Randall would rather not have anything to do with. Alternatively Randall just dislikes this map projection so much due to the above mentioned major inaccuracies, that he hates anyone who likes it.

{{clear}}

===Title text===
The title text makes a joke that goes to the familiar meme from ''{{w|CSI: Miami}}'', in which the star, David Caruso starts a sentence, then puts on his sunglasses and ends the sentence with a corny pun. In this case, the pun is on {{w|map projection}} and {{w|projection (psychology)|projection}} in psychology. Psychological projection is an unconscious defense mechanism wherein a person who is uncomfortable with their own impulses denies having them and attributes them to other people, and blames these people for these impulses. The Sunglasses internet meme has been used [[:Category:Puts on sunglasses|in other comics]] as well.

==Transcript==
:What your favorite
:'''Map Projection'''
:says about you
:[All of these are organized as Title, a copy of the particular projection underneath, and what it says about you under that.]

:*Mercator
:**You're not really into maps.
:*Van der Grinten
:**You're not a complicated person. You love the Mercator projection; you just wish it weren't square. The Earth's not a square, it's a circle. You like circles. Today is gonna be a good day!
:*Robinson
:**You have a comfortable pair of running shoes that you wear everywhere. You like coffee and enjoy The Beatles. You think the Robinson is the best-looking projection, hands down.
:*Dymaxion
:**You like Isaac Asimov, XML, and shoes with toes. You think the Segway got a bad rap. You own 3D goggles, which you use to view rotating models of better 3D goggles. You type in Dvorak.
:*Winkel-Tripel
:**National Geographic adopted the Winkel-Tripel in 1998, but you've been a W-T fan since ''long'' before "Nat Geo" showed up. You're worried it's getting played out, and are thinking of switching to the Kavrayskiy. You once left a party in disgust when a guest showed up wearing shoes with toes. Your favorite musical genre is "Post–".
:*Goode Homolosine
:**They say mapping the Earth on a 2D surface is like flattening an orange peel, which seems enough to you. You like easy solutions.You think we wouldn't have so many problems if we'd just elect ''normal'' people to Congress instead of Politicians. You think airlines should just buy food from the restaurants near the gates and serve ''that'' on board. You change your car's oil, but secretly wonder if you really ''need'' to.
:*Hobo-Dyer
:**You want to avoid cultural imperialism, but you've heard bad things about Gall-Peters. You're conflict-averse and buy organic. You use a recently-invented set of gender-neutral pronouns and think that what the world needs is a revolution in consciousness.
:*Plate Carrée (Equirectangular)
:**You think this one is fine. You like how X and Y map to latitude and longitude. The other projections overcomplicate things. You want me to stop asking about maps so you can enjoy dinner.
:*A Globe!
:**Yes, you're very clever.
:*Waterman Butterfly
:**Really? You know the Waterman? Have you seen the 1909 Cahill Map it's based— ...You have a framed reproduction at home?! Whoa. ...Listen, forget these questions. Are you doing anything tonight?
:*Peirce Quincuncial
:**You think that when we look at a map, what we really see is ourselves. After you first saw ''Inception'', you sat silent in the theater for six hours. It freaks you out to realize that everyone around you has a skeleton inside them. You ''have'' really looked at your hands.
:*Gall-Peters
:**I ''hate'' you.

{{comic discussion}}

[[Category:Maps‏‎]]
[[Category:Dvorak]]
[[Category:Puts on sunglasses]]
[[Category:Puns]]
[[Category:Aviation]]

Header text

2023-08-31T20:11:44Z

Capybarafan436: /* Global header text */ New header. This is basically just a skeleton, feel free to edit it and make it more detailed!

[[File:xkcd_header.png|thumb|left|250px|The header segment on [[xkcd|xkcd.com]]]]{{TOC}}The '''header text''' is updated whenever Randall has news to share. However, after the novelty of the news ends, the page usually goes back to its default header text, which states:

:xkcd updates every Monday, Wednesday, and Friday.

Usually, changes to the header text show up in all comics. However, in certain cases, the header text of a specific comic is changed permanently, which means it won't be modified like the rest of the comics.

==Comic-specific header text==
{{incomplete|This list is missing many comic-specific header texts. Don't remove this notice unless they're all mentioned here. [[Talk:header_text#1047|See the Talk page]] for some examples.}}

When editing the section, list the changes chronologically with the date of the web archive link and hyperlink each date. Include an internal link to the comic at the time of each change and describe the modifications with relevant information. Place the most recent changes at the top.

===Instructions===
*[[2601: Instructions]]
**This comic's header mentions the people who helped put it together.
***It was on the front page from Friday [https://web.archive.org/web/20220401210146/https://xkcd.com/ 2022-04-01] until Monday [ 2022-04-04], until the new comic was released on Monday.
****Expect there to be a page from April 4, but at this point there is one from [https://web.archive.org/web/20220406124444/https://xkcd.com/ 2022-04-06] showing the front page having returned to normal header.
**The text:
***Today's comic was created with [https://twitter.com/fadinginterest Patrick], [https://twitter.com/Aiiane Amber], [https://twitter.com/chromakode @chromakode], [https://twitter.com/dyfrgi Michael], [https://twitter.com/wirehead2501 Kat], [https://twitter.com/xDirtyPunkx Conor], [https://twitter.com/zigdon @zigdon], and [https://twitter.com/bstaffin Benjamin Staffin].
**It thanks those that helped Randall create that years [[:Category:April fools' comics|April fools' comic]].
***All have a link to their name, the first with an Instagram page, the other seven with a link to their Twitter account. Five of those also helped with the previous April Fools' comic, see below.
**Since this header was related only to the Fools' comic, it was removed from the frontpage header, when the next comic was released.
***But it stayed up as one of the permanent different headers on this comic, as seen two days after it stopped being on the front page on [https://web.archive.org/web/20220406021357/https://xkcd.com/2601/ 2022-04-06].
**See the comic on xkcd {{xkcd|2601}}.

===Checkbox===
*[[2445: Checkbox]]
**This comic's header mentions the people who helped put it together.
***It was on the front page from Thursday [https://web.archive.org/web/20210401232108/https://xkcd.com/ 2021-04-01] until Monday [https://web.archive.org/web/20210405130031/http://xkcd.com/ 2021-04-05], until the new comic was released on Monday.
**The text:
***This comic was put together by [https://chromakode.com/ Max Goodhart], [https://twitter.com/fadinginterest Patrick], [https://twitter.com/Aiiane Amber], [https://twitter.com/bstaffin Benjamin Staffin], [https://twitter.com/cotrone Kevin Cotrone], [https://twitter.com/wirehead2501 Kat], and [https://twitter.com/dyfrgi Michael Leuchtenburg].
**It thanks those that helped Randall create that years [[:Category:April fools' comics|April fools' comic]].
***All have a link to their name, the first with a personal home page, the other six with a link to their Twitter account. Five of those also helped with the previous April Fools' comic, see below.
**Since this header was related only to the Fools' comic, it was removed from the front page header, when the next comic was released, here from the day after that release Tuesday [https://web.archive.org/web/20210406143023/http://xkcd.com/ 2021-04-06].
**But it stayed up as one of the permanent different headers on this comic, as seen two days later on [https://web.archive.org/web/20210407203547/https://xkcd.com/2445/ 2021-04-07].
**See the comic on xkcd {{xkcd|2445}}.

===Collector's Edition===
*[[2288: Collector's Edition]]
**This comic's header mentions the people who helped put it together.
***It was on the front page only for about a day around April 3rd and [https://web.archive.org/web/20200404014814/http://xkcd.com/#-370,-277vApril 4th 2020].
**The text:
***Today's comic was put together by [https://chromakode.com/ Max Goodhart], [https://twitter.com/Aiiane Amber], [https://twitter.com/bstaffin Benjamin Staffin], [https://twitter.com/cotrone Kevin], [https://www.instagram.com/fading_interest/ @fading_interest], [https://twitter.com/wirehead2501 Kat], [https://twitter.com/zigdon @zigdon], and Christopher Night.
****All names have links except the last.
**It thanks those that helped Randall create the 2020 [[:Category:April fools' comics|April fools' comic]], which had taken two extra days before it was released due to the complex nature of the comic.
*Due to the delay the next comic, [[2289: Scenario 4]], was released already the day after the Fool's comic, even though it was thus [[2289:_Scenario_4#Trivia|on a Saturday]]!
**Since this header was related only to the Fools' comic, it was removed from the front page header, when the next comic was released, but it stayed up as one of the permanent different headers on this comic
**See the comic on xkcd {{xkcd|2288}}.

=== Seven Years===
*[[1928: Seven Years]]
**[http://web.archive.org/web/20171214171157/https://xkcd.com/ 2017-12-14]
**It was released as a response to another cancer diagnosis, this is explained in the [[Design_of_xkcd.com#Header_text|Header text]] which has replaced the standard ''xkcd updates every Monday, Wednesday, and Friday.'' The new one is this one, with the active link included:
**The text (with link):
***Becky Beaton, sister of fellow cartoonist Kate Beaton, has also been diagnosed with cancer. You can support her treatment [https://www.youcaring.com/beckybeaton-1008390 here].
**{{w|Kate Beaton}} is the creator of the web comic [http://www.harkavagrant.com/ Hark! A Vagrant].
***Although this comic is not one on Randall's list of ''[[Design_of_xkcd.com#Comics_I_enjoy|Comics I enjoy]]'', he is clearly much influenced by another cancer diagnosis among someone in his own creative field.below.
**On [https://web.archive.org/web/20190817141450/https://www.xkcd.com/1928/ 2019-08-17], close to two years later, the message was still there and also [https://web.archive.org/web/20211226120634/https://xkcd.com/1928/ 2021-12-26] just past four years later.
***There was the possibility that it would be removed, when the support page was discontinued...
***But as that already happened before [http://web.archive.org/web/20181106124430/https://www.youcaring.com/beckybeaton-1008390 2018-11-06] it seems like it will be there to stay.
***Last archived version was from [http://web.archive.org/web/20180305022301/https://www.youcaring.com/beckybeaton-1008390 2018-03-05].
***Randall has previously done something similar for another friend, Emiliy, but [[#2014-11-27_-_Help_Emily|that header]] was not made permanent.
**See the comic on xkcd {{xkcd|1928}}.

===ISS Solar Transit 2===
*[[1830: ISS Solar Transit 2]]
**[https://web.archive.org/web/20170428041338/https://xkcd.com/ 2017-04-28]
**This header links back to [[1828: ISS Solar Transit]], a comic with the same joke setup released on the Monday of the same week
**See the comic on xkcd {{xkcd|1830}}.

===Meteorite Identification===
*[[1723: Meteorite Identification]]
**Randall realized that his comic was almost a copy of some other person. And he has since then acknowledged this on the comics specific page see more [[1723: Meteorite Identification#Trivia|here]].
**At the time of this post, in the newest saved version on the archive from [http://web.archive.org/web/20161010215516/http://xkcd.com/1723/ 2016-10-10] it is still there and says:
***Note: Jolyon, founder of [http://www.mindat.org/ mindat.org], made a similar chart way before me!
**See the comic on xkcd {{xkcd|1723}}.

===Substitutions 3===
*[[1679: Substitutions 3]]
**This was the third installment of Substitutions and as he did with [[#Substitutions 2|the second]] linking to the first and telling about browser extensions for this he did the same with this one:
**The text:
***(Previously: {{xkcd|1288|Substitutions}} and {{xkcd|1625|Substitutions 2}})
***Note: There are various [https://chrome.google.com/webstore/detail/replacerator/gaajhenbcclienfnniphiiambbbninnp?hl=en browser extensions] for this.
**It was on the main page while the comic was up, for instance here on [https://web.archive.org/web/20160512102325/http://xkcd.com/ 2016-05-12].
**See the comic on xkcd {{xkcd|1679}}.

=== Garden===
*[[1663: Garden]]
**This comic had a header text to help people use the comic when it came out.
**For some time this text was the main header text, but after a while is disappeared from the main header, but remained as the header for Garden.
***See more [[xkcd_Header_text#2016-04-04_-_Protip_on_Garden|below]] or on the Garden page [[Garden#Header_text_after_release|here]]
**Today and as of the newest saved version on the archive from [http://web.archive.org/web/20161231231600/http://xkcd.com/1663/ 2016-12-31] it is still there and says:
***Protip: If you don't like how your garden is growing, you can click to prune it.
***You can copy the URL to share your garden. From other browsers, it will be view-only.
**See the comic on xkcd {{xkcd|1663}}.

===Substitutions 2===
*[[1625: Substitutions 2]]
**This was the second installment of Substitutions and Randall links to the first and tells about browser extensions for this:
**The text:
***(Previously: {{xkcd|1288|Substitutions}})
***Note: There are various [https://chrome.google.com/webstore/detail/xkcd-substitutions/jkgogmboalmaijfgfhfepckdgjeopfhk?hl=en browser extensions] for this.
****He did the same when [[xkcd_Header_text#Substitutions_3|Substitutions 3]] came out, linking to the two previous.
**It was on the main page while the comic was up, for instance here on [https://web.archive.org/web/20160104171722/http://xkcd.com/ 2016-01-04].
**See the comic on xkcd {{xkcd|1625}}.

===United Shapes===
*[[1079: United Shapes]]
**The header was unique for this comic on the day it came out: [https://web.archive.org/web/20120709045709/http://xkcd.com:80/ 2012-07-09].
**The text:
***There's a larger version of this map [http://xkcd.com/1079/large/ here] (Colorado is [http://xkcd.com/1079/colorado/ here]).
***It's also available as a [https://web.archive.org/web/20120709045709/http://store.xkcd.com/xkcd/#StateMap poster].
**The text was never on other pages:
***Before US was released, also on [https://web.archive.org/web/20120709004956/http://www.xkcd.com/ 2012-07-09] the comic [[1078: Knights]] was on the main page, with the previous [[xkcd_Header_text#2012-04-09 -_Standard_text_plus_store_link|promotion of the store]].
***The US version was still on the front the day after [https://web.archive.org/web/20120710063424/http://xkcd.com/ 2012-07-10].
***But the same day [https://web.archive.org/web/20120710114846/http://xkcd.com/1078/ 2012-07-10] the page for Knights did show a new header, which may only have been active on other pages than the front on this day... See details here [[xkcd_Header_text#2012-07-10_-_New:_what-if.xkcd.com|New:_what-if.xkcd.com]]
****Here is another page from [https://web.archive.org/web/20120710095644/http://xkcd.com/1070/ 2012-07-10] with [[1070: Words for Small Sets]], that was also saved that day, so this was on the top of all other comics, except the front page.
**There are simply no version of the front page from the 11th and 12th of July 2012. But from other pages it can be shown that from the 11th there was a difference.
***On [https://web.archive.org/web/20120711223349/http://xkcd.com/1078/ 2012-07-11] on the page for Knights and for instance from the same day on page number [https://web.archive.org/web/20120711223339/http://xkcd.com:80/1077 1077] [[1077: Home Organization]] there is the same but new header, different than the one Knights had both two days before and the other one from the day before.
***And also on [https://web.archive.org/web/20120711123734/http://xkcd.com:80/1079/ 2012-07-11] the numbered page {{xkcd|1079}} for US displays a mix of this new and the unique version of the header text.
****It left our the part about Colorado and moved the bottom line up so the unique part is written in one line (that may still take up two lines as the text will spill over, (maybe just in some browsers?)
****And then it added the two lines of header text that was on all the other pages (presumably also the front page, but that was first proved with the version from [https://web.archive.org/web/20120713154207/http://xkcd.com/ 2012-07-13]).
****And this is the version still shown on {{xkcd|1079}} today, even though the bottom lines was a normal header that was supposed to disappear.
**The final text that is still on US today:
***There's a larger version of this map [http://xkcd.com/1079/large/ here]! It's also available as a [https://store.xkcd.com/collections/posters/products/united-shapes-poster poster].
***New: [https://what-if.xkcd.com/1/ what-if.xkcd.com]: abusing science to answer hypothetical questions.
***I'll answer a new reader question every Tuesday.
****Here above the link has been updated to the one in the current version, where as the above link in the original version, that is now a dead link, has been directed to an archived version of the stores poster.
****The link the new part is to the very first ''[[what if? (blog)|what if?]]'' article ''{{what if|1|Relativistic Baseball}}'' which was released on 2012-07-10, the day after US was released, but before the next comic [[1080: Visual Field]] was released on 2012-07-11.
*****There are no version of comic {{xkcd|1080}} archived while it was on the front page, so it is not possible to tell what the front page looked like on the 11th and 12th of July. But best guess is that it looked like that on Knight shown above from the 11th.
**The first version was on the main page while the comic was up.
***Maybe there was a time with the final version on the front page, but seems like Randall put the new header text there in hand, and forgot to delete it after, so he probably first changed it when the new comic came out.
***Since the new header was important, promoting his new ''what if'' blog, he likely did not wish to have a fairly new page (maybe even on the front page on the 10th) without the reference. Also he did not wish to remove the link to the poster in the store.
***But this makes it a special unique header, as a relic from the past header text is left together with the text that was supposed to be permanent. It should have been deleted when the link to ''what if'' 1 was removed.
**See the comic on xkcd {{xkcd|1079}}.

===Umwelt===
*[[1037: Umwelt]]
**It has a permanent promotion of the store already from the release day on [https://web.archive.org/web/20120401151639/http://xkcd.com:80/ 2012-04-01]:
**The unique text:
***You can get posters, prints, and t-shirts in the [https://store.xkcd.com/ xkcd store].
**It stayed on the front page while this comic was the most recent, so for instance also two days later on [https://web.archive.org/web/20120403223453/http://www.xkcd.com/ 2012-04-03]
***There was a different header on other comics even while this comic was on the front page with the unique text. See [[xkcd_Header_text#2012-03-28_-_Visiting_Newport_News|Visiting Newport News]].
**See the comic on xkcd {{xkcd|1037}}.

===s/keyboard/leopard/===
*[[1031: s/keyboard/leopard/]]
**In response to the idea of having you browser replace keyboard with leopard a reader made a script that could do just that.
**Randall seem to have gotten this script before release (or at least on the day of release) as it was already the header text on [https://web.archive.org/web/20120319130702/http://xkcd.com/ 2012-03-19] the day the comic was released.
**The unique text is:
***A helpful reader has provided an [https://userscripts.org/scripts/show/128626 s/keyboard/leopard/ user script].
****The link does not go anywhere useful any longer, but here is the archived version of the link from two days after the release of the comic on [https://web.archive.org/web/20120321174019/http://userscripts.org/scripts/show/128626 2012-03-21]
**It was never changed on the other comics so was only on the front while this comic was up until 2012-03-21
***Here also shown on the second day it was up on its own page on [https://web.archive.org/web/20120320143916/http://xkcd.com:80/1031/ 2012-03-20].
**The next comic [[1032: Networking]] came out on [https://web.archive.org/web/20120321205835/http://xkcd.com:80/ 2012-03-21] and here the header text has returned to what it was before the leopard comic: [[xkcd_Header_text#2012-03-12_-_xkcd_Holistic_Browser|xkcd Holistic Browser]].
***Here are examples from dates around this showing it was not used on other pages:
****The last archived version of the front page from before the 19th was this version from [https://web.archive.org/web/20120317121834/http://xkcd.com:80/ 2012-03-17], but here is an example from [https://web.archive.org/web/20120318153256/http://xkcd.com:80/1030/ 2012-03-18] (from comic [[1030: Keyed]]), the day before leopard comic came out.
****Both on [https://web.archive.org/web/20120319174700/http://xkcd.com/1030/ 2012-03-19] (from comic [[1030: Keyed]]) and on [https://web.archive.org/web/20120320191039/http://xkcd.com:80/1012 2012-03-20] (from comic [[1012: Wrong Superhero]]) during the time leopard was up, the header text currently in used was still shown.
**See the comic on xkcd {{xkcd|1031}}.

===Making Things Difficult===
*[[996: Making Things Difficult]]
**Randall links to a blog post about cancer as related to this cancer comic
**The unique text:
***Some context for the cancer comics:
***[https://blog.xkcd.com/2011/06/30/family-illness/ https://blog.xkcd.com/2011/06/30/family-illness/]
****The link is for post on his [[Blag]].
****It is on the oldest stored version from [https://web.archive.org/web/20111229043804/http://xkcd.com:80/ 2011-12-29] when it was on the header.
**See the comic on xkcd {{xkcd|996}}.

===Money===
*[[980: Money]]
**Randall notes his thoughts about making it and makes a promotion of the poster.
**The unique text:
***This one was fun (and exhausting) to make.
***There's a poster of it in the [https://store.xkcd.com/products/money-poster store]!
****It is both at the oldest stored version from [https://web.archive.org/web/20120404110059/http://xkcd.com:80/980 2012-04-04] and the newest at time of editing [https://web.archive.org/web/20220108132250/https://xkcd.com/980/ 2022-01-08].
**See the comic on xkcd {{xkcd|980}}.

===Map Projections===
*[[977: Map Projections]]
**Randall notes that a person had birthday on the release of this comic about maps, and this guy has maps on his homepage
**The unique text:
***It turns out Monday was Steve Waterman's birthday. His [https://web.archive.org/web/20111118003418/http://www.watermanpolyhedron.com/ site] has posters of his map, plus maybe the world's only Winkel Tripel-critiquing poetry.
****The link goes to [http://www.watermanpolyhedron.com/ Waterman project] home page. Above the link goes to an archived version from around the time of release of the header text.
****It is at the oldest stored version with the comic on the front page on [https://web.archive.org/web/20111115231643/http://xkcd.com:80/ 2011-11-15].
**See the comic on xkcd {{xkcd|977}}.

===Na===
*[[851: Na]]
**After Randall made this comic, he realized he could have "made it better" and changed the header text to:
***I can't ''believe'' I forgot Hey Jude.
***I don't get do-overs, but I couldn't resist making [https://xkcd.com/851_make_it_better/ a fixed version].
**See more about it in that comics [[851:_Na#Trivia|trivia section]].
**See the comic on xkcd {{xkcd|851}}.

===Malamanteau===
*[[739: Malamanteau]]
**Randall notices that he has changed this comics license, so it can be used on Wikipedia.
**The text:
***At Wikipedia's request, I release this comic under a [https://creativecommons.org/licenses/by-sa/3.0/us/ cc-by-sa] license.
****The link is to the page regarding {{w|Creative Commons license}} in the US.
****Specifically for Attribution-ShareAlike 3.0 United States (CC BY-SA 3.0 US)
*****Usually xkcd is [[Design_of_xkcd.com#License_and_copyright|shared under]] [http://creativecommons.org/licenses/by-nc/2.5/ Creative Commons Attribution-NonCommercial 2.5 License]. This does not allow commercial use, But the 3.0 does.
**When the comic came out it had the normal header text from that time, as seen here two days after release on [https://web.archive.org/web/20100514072436/http://xkcd.com/ 2010-05-14].
***First archived version with the unique text is from [https://web.archive.org/web/20100913003146/http://xkcd.com/739/ 2010-09-13], but the previous archived version of this comic is from [https://web.archive.org/web/20100713160533/http://xkcd.com:80/739/ 2010-07-13].
***So it happened somewhere in the two months in between. But at least it was not there the first two months after release, but there before four month after release.
**See the comic on xkcd {{xkcd|739}}.

===Steal This Comic===
*[[488: Steal This Comic]]
**Randall is tired of {{w|DRM}}, an acronym standing for Digital Rights Management. This comic displays this. He thus make a promotion of Amazon that sells music without DRM.
**The text:
***Note: the [https://www.amazon.com/MP3-Music-Download/b?ie=UTF8&node=163856011 Amazon.com MP3 store] sells DRM-free music. Kudos.
****The link is to Amazon MP3 music. Here is an archived version from [https://web.archive.org/web/20081001083843/http://www.amazon.com/MP3-Music-Download/b?ie=UTF8&node=163856011 2008-10-01], two weeks prior to the release of the comic.
**The header text was on the comic from the release day, here seen the day after on the first archived version from [https://web.archive.org/web/20081014232952/http://xkcd.com/ 2008-10-14].
**See the comic on xkcd {{xkcd|488}}.

===House of Pancakes===
*[[472: House of Pancakes]]
**This comic's header notes its status as a parody:
***(Today's comic is a parody of [https://www.amazon.com/House-Leaves-Mark-Z-Danielewski/dp/0375703764 House of Leaves].)
**Only on the days this comic was the newest was this header featured on the front page of xkcd for instance as seen here the day after release on [https://web.archive.org/web/20080906103932/http://www.xkcd.com/ 2008-09-06].
***But it was only on this comic. The commercial for his new t-shirt was on all the other pages, also on [https://web.archive.org/web/20080906103932/http://www.xkcd.com/ 2008-09-06] and presumably returned to the front page with the next comic. But there is a gap in the archive after this comic.
**See the comic on xkcd {{xkcd|472}}.

==Global header text==
When editing the section, list the changes chronologically with the date of the web archive link and hyperlink each date. Include an internal link to the newest comic at the time of each change and describe the modifications with relevant information. Position the last comic displaying the header text below the other data and place the most recent change at the top.
===2023-08-31 - What If? 2 is now available in paperback in the UK!===
*[http://web.archive.org/web/20230831200321/https://xkcd.com/ 2023-08-31]
**[[2822: *@gmail.com]] was the comic on the home page when the header changed.
**The header has the same layout as the past one and has two parts. The right picture remains the same, but the image has changed to text.

===2022-09-13 - What if? 2 is available now===
*[https://web.archive.org/web/20220913142432/https://xkcd.com/ 2022-09-13].
**[[2672: What If? 2 Flowchart]] was released as the header changed, even though it was a Tuesday.
***The header and the comic celebrates the release of the new what if? 2 book, that came out on this day.
**The header kept the same layout as the previous and thus still consist of two parts. With the right picture the window also used in [[#2022-01-10 - Standard text with countdown|the countdown]], but with the image that appeared in it after the count down ended.
***The image is taken from the front cover of the new book, with red background, showing a passenger plane taking off with the wheels still down. On top of it a Tyrannosaurus Rex has begun eating its way into the plane. Below the plan is the book title in white text.
**The new image to the left has a black border. To the left is still the picture of the new what if? 2 book. It has the same image as in the picture to the right, but showing the entire front of the book, with details of those looking up at the plane from the ground. The title and the author name can be read in white on the red book. There are also unreadable white text above the plane and below the author name. The spine of the book can also be seen, as the book is seen a bit from the side. Here are also unreadable white text. To the right of the book there are two lines of text, with the first line in very large bold letters
**The text:
***what if? 2
***Randall Munroe
***What if? 2 is available now!
***what if? 2
****Both images are links that goes to a dedicated page on xkcd about [https://xkcd.com/what-if-2/ what if? 2: the book].
*This thus ended the pre-release promotion of the book, that began on [[#xkcd_Header_text#2022-01-31_-_What_if.3F_2|2022-01-31]], plus of course the three weeks of [[#2022-01-10 - Standard text with countdown|countdown]] before. For a sum total of 8 months and three days.
**It will be interesting to see how long before any reference to what if? 2 will disappear from the header text.

===2022-09-12 - One day to What if? 2 comes out===
*[https://web.archive.org/web/20220912125617/https://xkcd.com/ 2022-09-12]
**This was while [[2670: Interruption]] was still up.
**The header is the same layout as the previous and thus still consist of two parts. With the right picture the window also used in [[#2022-01-10 - Standard text with countdown|the countdown]], but with the image that appeared in it after the count down ended.
***The image is taken from the front cover of the new book, with red background, showing a passenger plane taking off with the wheels still down. On top of it a Tyrannosaurus Rex has begun eating its way into the plane. Below the plan is the book title in white text.
**The new image to the left has a black border. To the left is still the picture of the new what if? 2 book. It has the same image as in the picture to the right, but showing the entire front of the book, with details of those looking up at he plane from the ground. The title and the author name can be read in white on the red book. There are also unreadable white text above the plane and below the author name. The spine of the book can also be seen, as the book is seen a bit from the side. Here are also unreadable white text. To the right of the book there are three lines of text. With the first line written in large bold letters. This also has a footnote star. And the footnote is then written to the right in smaller font over five lines of text.
**The text:
***what if? 2
***Randall Munroe
***One day* until what if? 2 comes out!
***<nowiki>*</nowiki>I'm going to spend the day with that Les Mis song stuck in my head, aren't I.
***what if? 2
****Both images are links that goes to a dedicated page on xkcd about [https://xkcd.com/what-if-2/ what if? 2: the book].
**The foot note refers to the [[2636: What If? 2 Countdown]]. For the date where the header changed 2022-09-12 it was ''F(99) where F(N) means sing all the verses of N Bottles of Beer On the wall followed by F(N-1)'' to release day.
***It is thus for certain this song Randall mentions will now be stuck in his head.
***Les mis song, probably meaning les miserables song, as in a horrible song, he now has stuck in his head for an entire day.
**The header stayed the same until [https://web.archive.org/web/20220913134002/https://xkcd.com/ 2022-09-13].
***This was while [[2671: Rotation]] was still up, early on the release day of the new book.

===2022-09-12 - Three days to What if? 2 comes out===
*[https://web.archive.org/web/20220911102450/https://xkcd.com/ 2022-09-11]
**This was while [[2670: Interruption]] was still up.
**The header is the same layout as the previous and thus still consist of two parts. With the right picture the window also used in [[#2022-01-10 - Standard text with countdown|the countdown]], but with the image that appeared in it after the count down ended.
***The image is taken from the front cover of the new book, with red background, showing a passenger plane taking off with the wheels still down. On top of it a Tyrannosaurus Rex has begun eating its way into the plane. Below the plan is the book title in white text.
**The new image to the left has a black border. To the left is still the picture of the new what if? 2 book. It has the same image as in the picture to the right, but showing the entire front of the book, with details of those looking up at he plane from the ground. The title and the author name can be read in white on the red book. There are also unreadable white text above the plane and below the author name. The spine of the book can also be seen, as the book is seen a bit from the side. Here are also unreadable white text. To the right of the book there are three lines of text. With the first line written in large bold letters. This also has a footnote star. And the footnote is then written to the right in smaller font over five lines of text.
**The text:
***what if? 2
***Randall Munroe
***Three days* until what if? 2 comes out!
***<nowiki>*</nowiki>Assuming it's still Saturday. I'm a static png image and can't perceive time.
***what if? 2
****Both images are links that goes to a dedicated page on xkcd about [https://xkcd.com/what-if-2/ what if? 2: the book].
**The header only stayed the same for one day and [[2670: Interruption]] was still up when it changed to the next.

===2022-09-07 - Less than one week to What if? 2 comes out===
*[https://web.archive.org/web/20220907211736/https://xkcd.com/ 2022-09-07]
**This was while [[2668: Artemis Quote]] was still up.
**The header still consist of two parts. With the right picture the window also used in [[#2022-01-10 - Standard text with countdown|the countdown]], but with the image that appeared in it after the count down ended.
***The image is taken from the front cover of the new book, with red background, showing a passenger plane taking off with the wheels still down. On top of it a Tyrannosaurus Rex has begun eating its way into the plane. Below the plane is the book title in white text.
**The new image to the left has a black border. To the left is still the picture of the new what if? 2 book. It has the same image as in the picture to the right, but showing the entire front of the book, with details of those looking up at he plane from the ground. The title and the author name can be read in white on the red book. There are also unreadable white text above the plane and below the author name. The spine of the book can also be seen, as the book is seen a bit from the side. Here are also unreadable white text. To the right of the book there are four lines of text. With the middle line written in large bold letters. This also has a footnote star. And the footnote is then written to the right in smaller font over four lines of text.
**The text:
***what if? 2
***Randall Munroe
***Less than one week* until what if? 2 comes out!
***<nowiki>*</nowiki>Oh no, now I have that song stuck in my head.
***what if? 2
****Both images are links that goes to a dedicated page on xkcd about [https://xkcd.com/what-if-2/ what if? 2: the book].
**The foot note refers to the [[2636: What If? 2 Countdown]]. For the date where the header changed 2022-09-07 it was ''one pico-universe-lifetime'' to release day. But the next day 2022-09-08 it was ''The Baby Shark chorus for a family of 50,000 sharks''.
***It is thus for certain this song Randall mentions will now be stuck in his head.
**The header stayed the same until [https://web.archive.org/web/20220910024549/https://xkcd.com/ 2022-09-10].
***This was while [[2670: Interruption]] was up.

===2022-08-27 - Preorder What if? 2 - with image - again===
*[https://web.archive.org/web/20220827232205/https://xkcd.com/ 2022-08-27]
**[[2664: Cloud Swirls]] came out when it changed.
**The header [[#2022-08-16 - Preorder What if? 2 - with image|changed back]] to the preorder image from the previous header, when Randall's book tour ended. See the link.
*It ended on [https://web.archive.org/web/20220906191403/https://xkcd.com/ 2022-09-06].
**This was while [[2668: Artemis Quote]] was up.

===2022-08-17 - What if? 2 book tour===
*[https://web.archive.org/web/20220817161136/https://xkcd.com/ 2022-08-17]
**[[2659: Unreliable Connection]] was out when it changed.
**The header still consist of two parts. With the right picture the window also used in [[#2022-01-10 - Standard text with countdown|the countdown]], but with the image that appeared in it after the count down ended.
***The image is taken from the front cover of the new book, with red background, showing a passenger plane taking off with the wheels still down. On top of it a Tyrannosaurus Rex has begun eating its way into the plane. Below the plan is the book title in white text.
**The new image to the left has a black border. Inside this there is text to the left. Then Cueball is seen flying by holding on to a single balloon (like in [[1110: Click and Drag]]). He flies over five mountain peaks with snow, with three clouds and three distant birds in front of him, as he drifts to the right, as shown with movements lines behind him. In front of him is a dark feature at the bottom of the frame. Above this is a blue square (like a button) with white text.
**The text:
***I'm going on a what if? 2 book tour!
***Click to see where
***what if? 2
****The image to the left is a link to [https://xkcd.com/events/ randall munroe: events] page on xkcd. Which at the time showed the calendar with the planned stop for his book tour, which covered the US and London.
****As always the link button in blue is not the only part of the image that is a link, as he just mentioned in the [[#2022-08-11 - Preorder What if? 2 - with image|previous header text]], and several times before...
****The right image is a link that goes to a dedicated page on xkcd about [https://xkcd.com/what-if-2/ what if? 2: the book].
*This header thus continues the promotion of the new book, which was at the time was only 27 days away (or [[2636:_What_If%3F_2_Countdown|6 dog months]]).
**It will be interesting to see how long it takes before promotion for the book disappears from the header. It may still take months.
*The header stayed the same until [https://web.archive.org/web/20220826202043/https://xkcd.com/ 2022-08-26].
**This was while [[2663: Tetherball Configurations]] was up.

===2022-08-11 - Preorder What if? 2 - with image===
*[https://web.archive.org/web/20220811055445/https://xkcd.com/ 2022-08-11]
**[[2657: Complex Vowels]] came out as it changed.
*The message in the header was not really changed, but the meaning of the text from the previous header was now written in an image, although the text did change somewhat.
**The header thus still consist of two parts. To the left the new image with an picture of the book and text. And to the right the window also used in [[#2022-01-10 - Standard text with countdown|the countdown]], but with the image that appeared in it after the count down ended.
***The image is taken from the front cover of the new book, with red background, showing a passenger plane taking off with the wheels still down. On top of it a Tyrannosaurus Rex has begun eating its way into the plane. Below the plan is the book title in white text.
**The new image to the left has a black border. Inside this to the right is the new text. To the left is a picture of the new what if? 2 book. It has the same image as in the picture to the right, but showing the entire front of the book, with details of those looking up at he plane from the ground. The title and the author name can be read in white on the red book. There are also unreadable white text above the plane and below the author name. The spine of the book can also be seen, as the book is seen a bit from the side. Here are also unreadable white text.
**The text:
***what if? 2
***Randall Munroe
***Preorder what if? 2 and enter for a chance to win a comic inspired by your question! Click here to learn more. Or click wherever. This whole image is a link because html is hard.
***what if? 2
****In the left image there is a blue link font on the word "here" in click here. However the entire left image is a link to the [https://sites.prh.com/whatif2 what if 2 contest]. As explained he did not only make the word a link because html is hard! This is something Randall [[xkcd_Header_text#2014-07-23_-_what_if.3F_book_tour|often comments on]].
*****The link in the text goes to a contest page that starts with the words:
*****[https://web.archive.org/web/20220718171904/https://sites.prh.com/whatif2 Want Randall Munroe to answer you What If? question?]
*****Here above the web archive version of the link, in case the link from the text goes dead in the future.
****The right image is a link that goes to a dedicated page on xkcd about [https://xkcd.com/what-if-2/ what if? 2: the book].
**The header stayed the same until [https://web.archive.org/web/20220816124823/https://xkcd.com/ 2022-08-16].
***This was while [[2659: Unreliable Connection]] was up.

===2022-07-19 - Preorder What if? 2===
*[https://web.archive.org/web/20220719153239/https://xkcd.com/ 2022-07-19]
**[[2647: Capri Suns]] came out as it changed.
*The header looked a lot like the previous one, only part of the text changed.
**The header thus still consist of two part. To the left a line of text (split up, most likely over four lines for most users). And to the right the window also used in [[#2022-01-10 - Standard text with countdown|the countdown]], but with the image that appeared in it after the count down ended.
***The image is taken from the front cover of the new book, with red background, showing a passenger plane taking off with the wheels still down. On top of it a Tyrannosaurus Rex has begun eating its way into the plane. Below the plan is the book title in white text.
**The text:
***Preorder What If? 2 (all US preorders eligible) and [https://sites.prh.com/whatif2 enter our contest] for a chance to win a dedicated comic and What If blog post!
***what if? 2
****The image is a link that goes to a dedicated page on xkcd about [https://xkcd.com/what-if-2/ what if? 2: the book].
***The link in the text goes to a contest page that starts with the words:
****[https://web.archive.org/web/20220718171904/https://sites.prh.com/whatif2 Want Randall Munroe to answer you What If? question?]
****Here above the web archive version of the link, in case the link from the text goes dead in the future.
**The header stayed the same until [https://web.archive.org/web/20220810034709/https://xkcd.com/ 2022-08-10].
***This was while [[2656: Scientific Field Prefixes]] was up.

===2022-01-31 - What if? 2===
*[https://web.archive.org/web/20220201000434/https://xkcd.com/ 2022-02-01]
**[[2575: What If? 2]] came out as it changed, and then it [https://www.explainxkcd.com/wiki/images/3/36/Countdown_in_header_text_page_when_what_if_comic_came_out.png looked like this] already on 2022-01-31. But there is no archived version from that day after the header changed.
***This was what [[#2022-01-10 - Standard text with countdown|the countdown]] had been counting down to.
***An announcement that Randall had written a sequel to the first ''[[What If? (book)|What If?]]'' book, based on his blog.
**The header consist of two part. To the left a line of text (split up, most likely over three lines for most users). And to the right the window also used in the countdown, but with the image that appeared in it after the count down ended.
***The image is taken from the front cover of the new book, with red background, showing a passenger plane taking off with the wheels still down. On top of it a Tyrannosaurus Rex has begun eating its way into the plane. Below the plan ia the book title in white text.
**The text:
***What If? 2: Additional Serious Scientific Answers to Absurd Hypothetical Questions comes out 9/13. Preorder [https://xkcd.com/what-if-2/ here!]
***What If? 2:
****The link goes to a dedicated page on xkcd about what if? 2: the book. The image is also a link to this page.
****The entire comic that came out along with the new header text is also a link to that page.
**At the same time the [[Design_of_xkcd.com#xkcd_links|xkcd links]] in the top left section of xkcd also changed to include links to books, and especially this new book.
*It will be interesting to see how long this version of the promotion for the new books stays up. But most likely there will be promotion for the book until release, and then more after the release.
**The header stayed the same until [https://web.archive.org/web/20220718145816/https://xkcd.com/ 2022-07-18], for more than 5,5 month. This was while [[2646: Minkowski Space]] was up.
***The change was rather small, but part of the text changed. The promotion continued though.

===2022-01-10 - Standard text with countdown===
*[https://web.archive.org/web/20220110183238/https://xkcd.com/ 2022-01-10].
**[[2565: Latency]] was still up when the [[Countdown in header text]] was added.
**The text was still the standard xkcd header: xkcd updates every Monday, Wednesday, and Friday.
**But a countdown was added. This was inserted in a rectangular box, placed at the end of the standard header text.
***In some browsers the box forces the last word "Friday" to jump down to the next line.
**Inside the box the following time was displayed in the version in the link:
***20d 20h 27m
****This clock will also count down every minute, although it will return to the time at the time of archive when reloaded!
****While this was edited into this wiki the time had changed to 20d 19h 12m. So it was a very fresh download in the web archive, only about 1 hour old when it was updated to this wiki.
****The minutes change without refreshing the page, and follows this editors computers clock exactly, so it will end at 59 minutes, not at a full hour.
***It looks like it started on [https://munvoseli.github.io/xkcd-countdown/ 01-10 17:00 UTC].
****A calculation shows that this countdown will reach zero on Monday 2022-01-31 at 14:59 (2:59 PM) {{w|UTC}}.
****This will be at 9:59 (9:59 AM) in [[Randall]]'s home town
*****The last ten minutes it switched to seconds for the last minute so it made the switch 15:00 UTC 10:00 in Boston!
****From that it can be deduced that the count started at 20d 22h 0m
*****The first image on the archive thus came 1h 33m after the count began.
**At [https://web.archive.org/web/20220111153818/https://xkcd.com/ 2022-01-11] a diagonal black bar appeared in the lower left-hand corner of the countdown box.
***After that the [[Countdown in header text]] page was created and any further development on the count down will be mentioned on that page.
*It was last up on [https://web.archive.org/web/20220131124817/https://xkcd.com/ 2022-01-31] when [[2574: Autoresponder]] was on the front page.
**This archived version was when the counter was at 0d 2h 11m, and the last normal frame was already up at this time.
***It stayed like this until the [https://www.explainxkcd.com/wiki/images/1/17/Countdown_in_header_text_page_0_seconds.png counter ran out].
****Then for a few minutes the final frame, that revealed that all this was a promotion for Randall's new book what if? 2 was up [https://www.explainxkcd.com/wiki/images/4/48/Countdown_in_header_text_page_just_after_countdown.png while the Friday comic was still up].
****Then when the new Monday comic came out with the promotion for what if? 2, the header changed.

===2022-01-08 - Back to standard text===
*[https://web.archive.org/web/20220108044654/https://xkcd.com/ 2022-01-08].
**[[2565: Latency]] came out around the time the new header text appeared, on a Friday!
**The text returned to the standard xkcd header:
***xkcd updates every Monday, Wednesday, and Friday.
**This was the first time since [[#2018-11-07 - Back to standard text|2018-11-07]] that the text had changed back to that, and at that time it lasted until 2019-02-05.
***That is 1067 days (less than a month short of three years) without the standard text! (Can it be called standard anymore?)
**It was only left in the complete standard version until [https://web.archive.org/web/20220109030513/https://xkcd.com/ 2022-01-09] when Latency was still on the front page.
***Then the next day a [[#2022-01-10 - Standard text with countdown|countdown]] was added to it.
****That was after the weekend on Monday but before the Monday comic came up.
****So only during the weekend was it normal standard header text.

===2021-12-20 - What If in stock===
*[https://web.archive.org/web/20211220211220/https://xkcd.com/ 2021-12-20].
**[[2557: Immunity]] came out around the time the new header text appeared.
**The text:
***For anyone trying to find What If? this year, it's in stock at [https://www.barnesandnoble.com/w/what-if-serious-scientific-answers-to-absurd-hypothetical-questions-randall-munroe/1118864093 Barnes & Noble], [https://m.booksamillion.com/p/What-If/Randall-Munroe/9780544272996 Books-a-Million], and [https://bookshop.org/books/what-if-serious-scientific-answers-to-absurd-hypothetical-questions-9781483041827/9780544272996 Bookshop]
**Each store name is a link to the corresponding store's page for ''[[What If? (book)|What If?]]''.
*It was last seen on [https://web.archive.org/web/20220106100957/https://xkcd.com/ 2022-01-06] when [[2564: Sunshield]] was up.

===2020-06-03 - Black Lives Matter===
*[https://web.archive.org/web/20200604003700/http://xkcd.com/ 2020-06-03].
**[[2315: Eventual Consistency]] came out as a new header text was finally inserted after almost two months without one.
**Cueball is standing to the left and speaks a single line of text: "Black Lives Matter"
**To the right is a gray link button with text: "[https://www.joincampaignzero.org/ How To Help]."
**As always, the entire image (which is only below the xkcd logo) is a link
***The button is thus not needed, but it will also work when clicking the location of the button.
**The link goes to [https://www.joincampaignzero.org/ Join Campaign Zero].
***{{w|Black Lives Matter}} is a loose, grassroots, decentralized confederation of groups and individuals advocating for racial justice. It arose in 2013 after the acquittal of {{w|George Zimmerman}}, who took the life of {{w|Trayvon Martin}}.
***Randall's featuring Black Lives Matter came on the heels of the {{w|Killing of George Floyd}} on May 25th 2020, which had sparked {{w|George Floyd protests|protest in the US}}
***Floyd died while saying "{{w|I can't breathe}}," which was already used due to other Black men's killings, the first was from the {{w|Killing of Eric Garner}}, back in 2014.
*It stayed like this until [https://web.archive.org/web/20200616114945/https://xkcd.com/ 2020-06-16] when [[2320: Millennium Problems]] was up.
**Then on [https://web.archive.org/web/20200617131438/https://xkcd.com/ 2020-06-17] the link changed to [https://blacklivesmatter.com/ Black Lives Matter]. [[2320: Millennium Problems]] was still on the front page on that day.
*On April 1st 2021 the front page header changed to mention who made the April Fools' comic.
**But this was only for this comic [[#Checkbox|Checkbox]].
**The rest of the pages kept the BLM header and it returned to this on the front page once the next comic was released on April 5th. At that time it will have been up for 13 months, making it the longest header different from the standard header.
*It was last up on [https://web.archive.org/web/20211219202204/https://xkcd.com/ 2021-12-19] when [[2556: Turing Complete]] was on the front page.
**At that time it had been up for 564 days or 1,5 year plus 16 days! This is most likely a record.

===2020-04-05 - Empty header===
*[https://web.archive.org/web/20200405042955/https://xkcd.com/ 2020-04-05].
**[[2289: Scenario 4]] came out and the header belonging to the previous comic was removed.
**But no new header was inserted. Not even the go to [[#Header text|Header text]] about the release days of xkcd.
***Since the previous header was related only to the [[:Category:April fools' comics|April fools' comic]] [[2288: Collector's Edition]], and that had stopped the promotion of the [[How To]] book, after first experiencing problems with it's release, it seems Randall forgot what he usually put in the header.
*It stayed empty like this until [https://web.archive.org/web/20200602213017/https://xkcd.com/ 2020-06-02] when [[2314: Carcinization]] was on the front page.
**So almost two month without a header. This had not happened before.

===2020-04-04 - Put together by===
*[https://web.archive.org/web/20200404014814/http://xkcd.com/ 2020-04-04].
**[[2288: Collector's Edition]] came out and the header changed.
**The text:
***Today's comic was put together by [https://chromakode.com/ Max Goodhart], [https://twitter.com/Aiiane Amber], [https://twitter.com/bstaffin Benjamin Staffin], [https://twitter.com/cotrone Kevin], [https://www.instagram.com/fading_interest/ @fading_interest], [https://twitter.com/wirehead2501 Kat], [https://twitter.com/zigdon @zigdon], and Christopher Night.
****All names have links except the last.
**It thanks those that helped Randall create this years [[:Category:April fools' comics|April fools' comic]], which had taken two extra days before it was released due to the complex nature of the comic.
*Due to the delay the next comic, [[2289: Scenario 4]], was released already the day after the Fool's comic, even though it was thus [[2289:_Scenario_4#Trivia|on a Saturday]]!
**Since this header was related only to the Fool's comic, it was thus removed from the general header, but it stayed up as [[#Collector.27s_Edition|one of]] the permanent [[#Unique_header_text|unique header texts]].
***However, when it was removed from the general header, the header was left empty.
***Unlike some other headers that stayed on a given comic, this one was on all comics for the duration of the time it stayed on the front page, see for instance the previous comic on [https://web.archive.org/web/20200403232031/https://xkcd.com/2287/ 2020-04-03].

===2020-04-02 - Technical Reasons===
*[https://web.archive.org/web/20200402234828/https://xkcd.com/ 2020-04-02].
**[[2287: Pathogen Resistance]] was up when the header changed.
*Randall turned out to, again, have problems with his complicated and interactive [[:Category:April fools' comics|April fools' comic]] for 2020.
**The text:
***Note: For technical reasons Wednesday's comic will be posted Thursday instead. Apologies for the delay!
*This finally stopped the promotion of the [[How To]] book.
**It had then been part of the header for well over a year since [http://web.archive.org/web/20190206060904/https://xkcd.com/ 2019-02-06].
*It stayed up a day longer than planed as the fool's comic, [[2288: Collector's Edition]] was first released on Friday, so the note was still up on [https://web.archive.org/web/20200403012612/https://xkcd.com/ 2020-04-03].
**[[2287: Pathogen Resistance]] thus stayed two extra day on the front page, and the third comic of that week, [[2289: Scenario 4]] was released already the day after the Fool's comic, even though it was thus [[2289:_Scenario_4#Trivia|on a Saturday]]!

===2020-01-16 - How To explores - again===
*[https://web.archive.org/web/20200116190038/https://xkcd.com/ 2020-01-16].
**[[2255: Tattoo Ideas]] was still up when the header changed.
**The ongoing promotion of the book continued but here more than three weeks after Christmas the reference to Christmas was removed.
**The header then returned to the one from before Christmas:
***[[#2019-11-22 - How To explores|How To explores]] - see that for all other details.
*It was last up on [https://web.archive.org/web/20200401221435/https://xkcd.com/ 2020-04-01] when [[2287: Pathogen Resistance]] was on the front page.
**It was the problems with [[:Category:April fools' comics|April fools' comic]] of 2020 that finally stopped the promotion of the [[How To]] book.
**It had then been part of the header for well over a year since [http://web.archive.org/web/20190206060904/https://xkcd.com/ 2019-02-06].

===2019-12-02 - Into Science===
*[https://web.archive.org/web/20191202223745/https://xkcd.com/ 2019-12-02].
**[[2236: Is it Christmas?]] came out when the header changed. Fitting as the change is about Christmas list.
**Still promoting the new [[How To]] book, continuing to make the image a link to the [https://xkcd.com/how-to/ How To book] page on xkcd.
***The links below to order are the same as in the previous header.
***Actually most of the header stays the same with the same four images and the same layout. But the text above has changed completely and the two main text sections between the drawings has changed but only slightly. The description of the images is thus left out, see below. Only new thing is that there are now two red circles connected with a red arrow. The first circle is around the word How To at the end of the first text with the arrow going from that circle to the second circle drawn around the picture of the book.
**The text:
***Is there someone on you Christmas list who's into science? They might like my new book '''''How To'''''
***It explores ridiculous ideas for applying scientific research to everyday problems...
***...And illustrates what would happen if you tried them.
***''Boom''
***You can get it here:
***[https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 B&N], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound], [https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple], [https://www.audible.com/search?advsearchKeywords=How+To+Randall+Munroe&source_code=COMA0213WS031709&SID=PRHA9A5E24CFB--9780525635680 Audible], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/23/trackingcode/PRH3D17167A3B Target]
*It was last up on [https://web.archive.org/web/20200115155040/https://xkcd.com/ 2020-01-15] when [[2255: Tattoo Ideas]] was on the front page.

===2019-11-22 - How To explores===
*[https://web.archive.org/web/20191122214439/https://xkcd.com/ 2019-11-22].
**[[2232: Hotel Room Party]] was up when the header changed. It most likely changed when the comic appeared. Earlier on that day it was the previous header over the previous comic.
**Still promoting the new [[How To]] book, here again making the image a link to the [https://xkcd.com/how-to/ How To book] page on xkcd, after it previously was a link to where to listen to the audio book.
***The links below to order returns to the same as in the header before the previous header with links to audio books, except that the link to an exclusive edition has been removed.
***The header consist of an image with text above five small drawings with two text parts in between them. To the left is the closed How To book which is black with a blue readable title, How To, and unreadable white text below this as well as below the unreadable blue author name, which are below the image. The image shows Cueball putting in a light-bulb with drones under each foot while Megan, holding a ladder, and White/Black Hat are looking up at him. To the right of the book is a drawing of Ponytail pole-vaulting with two black helium filled balloons. Next to her is the first text segment. Then after that is the drawing, seen before in the header text, of a truck towing a house up a steep hill. This truck goes above the second text segment, with Cueball somersaulting above the text. Furthest right, above and just right of the text is an explosion with the sound written inside. Below the header image is some black text and then the links to where to get it as regular blue link text.
**The text:
***My new book '''''How To''''' explores the science behind spacecraft heat shields, butterfly metabolisms, and land border surveys...
***...By imagining ridiculous ideas for applying the research to you everyday life...
***...And illustrating what would happen if you tried them.
***''Boom''
***You can get it here:
***[https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 B&N], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound], [https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple], [https://www.audible.com/search?advsearchKeywords=How+To+Randall+Munroe&source_code=COMA0213WS031709&SID=PRHA9A5E24CFB--9780525635680 Audible], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/23/trackingcode/PRH3D17167A3B Target]
*It was last up on [https://web.archive.org/web/20191201191025/https://xkcd.com/ 2019-12-01] when [[2235: Group Chat Rules]] was on the front page.

===2019-11-06 - Audio clip===
*[https://web.archive.org/web/20191106204314/https://xkcd.com/ 2019-11-06].
**[[2224: Software Updates]] was still up when the header changed, but the first archive version was first from after the next comic came out [[2225: Voting Referendum]].
**Still promoting the new [[How To]] book, here making the image a link to the How To book on Penguin Random House's audio book, where an audio clip read by Wil Wheaton can be sampled.
***The links below to order have now changed to those with audio books.
***The header consist of an image with text, with a "blue link", above the How To book that is being folded out from closed; to partially open; to opened up on two full pages; this takes three images. The closed book is the black book with a blue readable title, How To, and unreadable white text below this as well as below the unreadable blue author name, which are below the image. The image shows Cueball putting in a light-bulb with drones under each foot while Megan, holding a ladder, and White/Black Hat are looking up at him. The partly open book still has this cover partly visible, but unreadable, as well as come unreadable text in the open side. The open book shows two pages with lots of unreadable text and three figures (maybe one is a table). Next to the open book there is an arrow to the right pointing at an audio icon with three audio lines in front. Below the header image are the links as regular text.
**The text:
***You can click here to hear a clip from the audio version of '''''How To''''', read by Wil Wheaton.
***[https://books.apple.com/us/audiobook/how-to-absurd-scientific-advice-for-common-real-world/id1475319694 Apple], [https://www.audiobooks.com/audiobook/how-to-absurd-scientific-advice-for-common-real-world-problems/369279 Audiobooks], [https://www.audible.co.uk/pd/How-To-Audiobook/1473680360?qid=1574679523&sr=1-1&pf_rd_p=c6e316b8-14da-418d-8f91-b3cad83c5183&pf_rd_r=DX3EZ14M14CFQPP9GHJY&ref=a_search_c3_lProduct_1_1 Audible], [https://play.google.com/store/books/details/Randall_Munroe_How_To?id=LzSGDwAAQBAJ Google Play], and [https://libro.fm/audiobooks/9780525635680 Libro.fm]
**The entire image is a link to the [https://www.penguinrandomhouseaudio.com/book/576760/how-to/ How To book on Penguin Random House] page, where the audio clip can he played.
***As always it is the entire picture that is a link, and not only the blue underlined text that says click here!
*It was last on the archive on [https://web.archive.org/web/20191122044456/https://xkcd.com/ 2019-11-22] when [[2231: the Time Before And After Land]] was on the front page. But it was most likely still up when [[2232: Hotel Room Party]] came out. But then changed during the next day.

===2019-10-02 - Horse vs football team===
*[https://web.archive.org/web/20191002005854/https://xkcd.com/ 2019-10-02].
**[[2210: College Athletes]] was up when the header changed.
**Still promoting the new [[How To]] book, but seeing this is no longer close to the release day the focus has changed. This time the image seems to be from one of the How To explanations in the book.
***The links below to order are the same as the previous header.
***But new text is added after the links to promote two events with Randall in New York the two days after this header came up.
****These links disappeared after a week leaving only the picture and the link to buy the book. See below.
***The header consist of an image with Cueball riding bareback on a horse. He comes from the left holding an American football. Running towards him from the right are eight American football players with helmets with three stars on the back of the helmet. Two of the players at the back are almost hidden by players in front of them. Beneath them is a line of text that belongs to the image, the period at the end of the sentence hangs in height with the center line of the last letter E... Then below the image follows the link and promotion of the NY events, these are written in regular.
**The text:
***My new book ''How To'' is out now! You can get it here.
***[https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 B&N], [https://www.barnesandnoble.com/w/how-to-randall-munroe/1130494832?ean=9780525686910#/ B&N Exclusive Edition], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound], [https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple], [https://www.audible.com/search?advsearchKeywords=How+To+Randall+Munroe&source_code=COMA0213WS031709&SID=PRHA9A5E24CFB--9780525635680 Audible], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/23/trackingcode/PRH3D17167A3B Target] I'll be at New York Comic Con! I'm giving [https://www.newyorkcomiccon.com/Explore/Panels/Panels-And-Screenings/#/event/how-todo-anything-with-randall-munroe-creator-of-xkcd a talk on Thursday], and on
***Friday [https://smbc-comics.com/ Zach Weinersmith] and I will be hosting [https://www.caveat.nyc/event/how-to--absurd-scientific-advice-for-common-real-world-problems-10-4-2019 an event at Caveat NYC].
**The image is a link to the [https://xkcd.com/how-to/ How To book page] on xkcd.
***The link to Target still seems to go the main page rather than to [https://intl.target.com/p/how-to-by-randall-munroe-hardcover/-/A-76508342 their How To book page]... Probably a still undiscovered error on Randall's part?
*This header changed, but so slightly that the changes will only be mentioned here rather than in a new section:
**The first link was last active on [https://web.archive.org/web/20191004014438/https://xkcd.com/ 2019-10-04]
**Then the day after only the second link remained from [https://web.archive.org/web/20191005041539/https://www.xkcd.com/ 2019-10-05]. [[2211: Hours Before Departure]] came out when it changed.
***But the text of this link changed as it had been a continues text from one to the other link. Also it was not entirely on it's own line, thus not as with the first link whose text was directly connected to the line with the links to buy the book.
***The new text of that link was:
****[https://smbc-comics.com/ Zach Weinersmith] and I will be hosting [https://www.caveat.nyc/event/how-to--absurd-scientific-advice-for-common-real-world-problems-10-4-2019 an event] Friday night at Caveat NYC!
****The last link was the same, but now it only covered two words not the entire end of the sentence.
***This other link was last active on [https://web.archive.org/web/20191007042707/https://xkcd.com/ 2019-10-07].
**And then the last link was gone by [https://web.archive.org/web/20191008053609/https://xkcd.com/ 2019-10-08], when [[2212: Cell Phone Functions]] came out.
*It ended on [https://web.archive.org/web/20191105164001/https://xkcd.com/ 2019-11-05] when [[2224: Software Updates]] was up.

===2019-09-30 - Tons of fun===
*[https://web.archive.org/web/20190930234245/https://xkcd.com/ 2019-09-30].
**[[2209: Fresh Pears]] was up when the header changed.
**Still promoting the new [[How To]] book, but seeing this is no longer close to the release day the focus has changed to how much fun it was for Randall to write it and how proud he is of the result. Randall, as Cueball, is saying this in the new header image.
***The links below to order are the same, except a new has been added at the end.
***The header consist of an image with Cueball standing to the left of the book, shown as tall as he is. The book is opened up on two pages with lots of unreadable text as well as three drawings, only one of these, with a circle diagram, can clearly be seen. Cueball is speaking, and the text is above him and the book. Two words are blue with a line under as if they where a link. But as always the entire image is a link. Beneath the image is the links on where to order the book.
**The text:
***Writing my new book '''''How To''''' was tons of fun and I'm so proud of the result. It's out now-Click Here to order!
***Order: [https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 B&N], [https://www.barnesandnoble.com/w/how-to-randall-munroe/1130494832?ean=9780525686910#/ B&N Exclusive Edition], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound], [https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple], [https://www.audible.com/search?advsearchKeywords=How+To+Randall+Munroe&source_code=COMA0213WS031709&SID=PRHA9A5E24CFB--9780525635680 Audible], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/23/trackingcode/PRH3D17167A3B Target]
**The image is a link to the [https://xkcd.com/how-to/ How To book page] on xkcd.
***The new link to Target seems to go the main page rather than to [https://intl.target.com/p/how-to-by-randall-munroe-hardcover/-/A-76508342 their How To book page]... Probably an error on Randall's part.
*It ended on October 2nd while [[2210: College Athletes]] where up. But there is no archived versions from the 1st of October and the one from the 2nd is with the next version. But the editor of this was making changes to the explanation of College Athletes before the next header change came along.

===2019-09-11 - How To available===
*[https://web.archive.org/web/20190911053115/https://xkcd.com/ 2019-09-11].
**[[2200: Unreachable State]] was still up when the header changed.
**The release day part of the promotion was changed to telling that the new [[How To]] book was available. With teasers about what is in the book below the heading. On either side of the text a picture of the book is still shown. Also the links below changed, adding three new and removing one old.
***The header consist of an image with the book shown both left and right of some text. Both books have blue title and author name, and white unreadable title and white drawing of Cueball flying on two quadcopters to put in a light-bulb in a ceiling lamp, while White/Black? Hat is watching together with Megan, who is holding a ladder. Beneath the image is the links on where to order it.
***Between the two books are two sections of text above each other, the lover with smaller font.
**The text:
***How To is available now!
***Learn how to open bottles with nuclear weapons and how to be on time for meetings by altering the Earths rotation. The book also features advice from real-life experts including Chris Hadfield and Serena Williams.
***Order: [https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 B&N], [https://www.barnesandnoble.com/w/how-to-randall-munroe/1130494832?ean=9780525686910#/ B&N Exclusive Edition], [http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound],[https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple], [https://www.audible.com/search?advsearchKeywords=How+To+Randall+Munroe&source_code=COMA0213WS031709&SID=PRHA9A5E24CFB--9780525635680 Audible]
**The image is a link to the [https://xkcd.com/how-to/ How To book page] on xkcd.
**{{w|Serena Williams}} is a famous tennis player who was also featured in one of the [[:Category:Book promotion|promotion comics]] for How To: [[2190: Serena Versus the Drones]]
**{{w|Chris Hadfield}} is a Canadian retired astronaut, engineer, and former Royal Canadian Air Force fighter pilot. The first Canadian to walk in space, Hadfield has flown two Space Shuttle missions and served as commander of the International Space Station.
***The new link to audible probably needs the user to be signed up, else it will go to the front page and ask yo to sign up. But from the archive the page can be seen [https://web.archive.org/web/20190923004816/https://www.audible.com/search?advsearchKeywords=How+To+Randall+Munroe&source_code=COMA0213WS031709&SID=PRHA9A5E24CFB--9780525635680 here].
*Up till [https://web.archive.org/web/20190922143253/https://xkcd.com/ 2019-09-22] it looked like this.
**Then on [https://web.archive.org/web/20190923145251/https://xkcd.com/ 2019-09-23] and extra link was added after Audible:
***[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/23/trackingcode/PRH3D17167A3B Target].
**[[2205: Types of Approximation]] was up when this change occurred during a weekend.
*It ended on [https://web.archive.org/web/20190929223547/https://xkcd.com/ 2019-09-29] when [[2208: Drone Fishing]] was up.

===2019-09-04 - Happy Release Day - bookstore===
*[https://web.archive.org/web/20190904051509/https://xkcd.com/ 2019-09-04].
**[[2198: Throw]] was already up when the header changed slightly, as the text below Happy release day changed.
*Most of the header stayed the same as the [[#2019-09-03 - Happy Release Day - calender|day before]], but the reference to the Gregorian/Julian calender was changed.
**The header consist of an image with the book shown both left and right of some text.Both books have blue title and author name, and white unreadable title and white drawing of Cueball flowing on two quadcopters to put in a light-bulb in a ceiling lamp, while White/Black? Hat is watching together with Megan comes who is holding a ladder. Beneath the image is the link on where to order it, now the preorder has been changed to order.
***Between the two books are two sections of text above each other, the lover with smaller font and in brackets.
**The text:
***Happy How To release day!
***Available wherever books are sold.
***(Mostly bookstores, I assume but you can always try your luck at Wendy's.)
**See below for any other details.
*It ended on [https://web.archive.org/web/20190909211737/https://xkcd.com/ 2019-09-09] when [[2200: Unreachable State]] was up.

===2019-09-03 - Happy Release Day - calendar===
*[https://web.archive.org/web/20190903051503/https://xkcd.com/ 2019-09-03]
**[[2197: Game Show]] was still up when the header changed, but it was for sure to coincide with [[2198: Throw]] which came out later on the release day while it still looked like in this version.
**Randall celebrated the release day of [[How To]], coming out the day the header changed.
***The comic is also a reference to a chapter in the book on how to throw things. A very complicated interactive comic where different persons or other living things can be chosen to throw dead or living things. The trow will then be shown below with distance measured in two units, normal and special. That is if the thrower can actually manage to throw the thing.
**The header consist of an image with the book shown both left and right of some text. The two black books have red stars around them, five on the outer side of the image and 6 on the inner, the stars are mirrored around left and right book. Both books have blue title and author name, and white unreadable title and white drawing of Cueball flying on two quadcopters to put in a light-bulb in a ceiling lamp, while White/Black? Hat is watching together with Megan, who is holding a ladder. Beneath the image is the link on where to order it, now the preorder has been changed to order.
***Between the two books are two sections of text above each other, the lover with smaller font and in brackets.
**The text:
***How To Randall Munroe
***Happy How To release day!*
***(*Gregorian calendar. The Julian edition doesn't come out for 13 more days.)
***How To Randall Munroe
***Order: [https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 Barnes & Noble],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound],[https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple Books]
**The image is a link to the [https://xkcd.com/how-to/ How To book page] on xkcd.
**Most of the world uses the {{w|Gregorian calendar}}, but before it was taken into use, the {{w|Julian calendar}} was in use.
***The Julian calendar does not take into account that every 100 years a leap year should be passed as in the Gregorian calendar, and thus it is at the moment 13 days behind, as it has has this many February 29th too many. Since there should actually be a leap year every 400 year, and the last of those was 2000, then it has been 13 days since 1900, and will stay like this until 2100 when it will become 14 days.
***The image is a link to the [https://xkcd.com/how-to/ How To book page] on xkcd.
**Already the next day the part of the header below happy release day about the Gregorian calender changed. See [[#2019-09-04 - Happy Release Day - bookstore|above]].

===2019-08-27 - Out in a week===
*[https://web.archive.org/web/20190827082224/https://xkcd.com/ 2019-08-27].
**[[2194: How to Send a File]] was up when the header changed.
**Randall continues to promote his new book, [[How To]], coming out a week from this header.
***It is only three lines of text
**The text:
***My new book, How To, comes out next week!
***Read an exclusive excerpt about transmission [https://blog.xkcd.com/2019/08/26/how-to-send-a-file/ here].
***[Four links in gray blue are given with the first words in black:] Preorder ''How To'': [https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 Barnes & Noble],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound],[https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple Books]
**Later [https://web.archive.org/web/20190827184229/https://xkcd.com/2194/ on the same day], (and here for the next day [https://web.archive.org/web/20190828095401/https://xkcd.com/ 2019-08-27] for the front page), more text and links where added, plus the order of the text was changed.
**The later text was:
***My new book, [https://xkcd.com/how-to/ How To], comes out in a week! ([https://blog.xkcd.com/2019/08/23/book-tour-and-contest-winner/ Book tour info])
***You can preorder it now to get a copy when it's released:
***[https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 Barnes & Noble],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound],[https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple Books]
***You can also read an exclusive excerpt about file transfers [https://blog.xkcd.com/2019/08/26/how-to-send-a-file/ here].
**The link to the book tour also include the winner of the [[#2019-06-25 - People with books|contest]] to get Randall to add "your" city to his book tour.
***The winner was {{w|Juneau, Alaska}}.
*It ended on the release day 2019-09-03, so this was last on the page on [https://web.archive.org/web/20190902042108/https://xkcd.com/ 2019-09-02].

===2019-08-06 - Win a sketch===
*[http://web.archive.org/web/20190806052948/https://xkcd.com/ 2019-08-06].
**[[2185: Cumulonimbus]] was up when the header changed.
***Most likely the header changed when that comic came out on 2019-08-05. But the previous header was also out during that day.
**Randall continues to promote his new book, [[How To]], now making a competition where you can win a stick figure sketch of yourself. (Although only for US residents!)
***The image shows Hairy, with a cat at his feet and Megan (or Danish?) with a samurai sword. They are standing with their backs towards each other, the cat on the left, Megan facing right with the sword towards the words.
***Below the drawing are links to places to preorder the book.
**The text:
***Want to win a sketch of yourself as a stick figure? [https://blog.xkcd.com/2019/08/05/win-an-xkcd-sketch/ Click here] to find out how!
***[Four links in gray blue are given with the first words in black:] Preorder ''How To'': [https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 Barnes & Noble],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound],[https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple Books]
****The entire picture is a [https://blog.xkcd.com/2019/08/05/win-an-xkcd-sketch/ link] to a [[Blag]] post: ''Win an xkcd sketch''
****That is even though only the click here part of the text is in blue, like a link.
****Cause as he often has written: I still haven't figured out HTML imagemaps, most recently in the [[#2019-07-09 - Drawings from How To|2019-07-09]] header.
*The header stayed like this until [https://web.archive.org/web/20190826062701/https://www.xkcd.com/ 2019-08-26] when [[2193: Well-Ordering Principle]] was up.

===2019-08-03 - First look inside===
*[http://web.archive.org/web/20190803222711/https://xkcd.com/ 2019-08-03].
**[[2184: Unpopular Opinions]] was up when the header changed.
**Randall continues to promote his new book, [[How To]], now stating that it comes out next month.
***Set to be released on September 3rd 2019, this update was made exactly one month before.
***The image shows text to the left of three drawings of the book: First the closed book showing the black front cover with blue and white text and white drawings, then the book is partly opened, and finally it lays opened up showing two pages, with a readable heading on the right page.
***Below the drawing are links to places to preorder the book.
**The text:
***My new book comes out next month. Click here for a first look inside!
***[On the books front cover only two thins can be read:]
****How To
****Randal Munroe.
***[These two words can also partly be read on the opening book.]
***[Only the large heading can be read on the right page of the open book:]
****How to Dig a Hole.
***[These two pages also became part of a special comic relased during the weekend when this header was up: [[Disappearing Sunday Update]].]
***[The [[Disappearing_Sunday_Update#Transcript|transcript of that comic]] describes the images in the open book.]
***[Four links in gray blue are given with the first word in black:] Preorder:[https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 Barnes & Noble],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound],[https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple Books]
****The entire picture is a [https://blog.xkcd.com/2019/08/02/how-to-chapter-list-and-introduction/ link] to a [[Blag]] post: ''How To: Chapter list and introduction''.
*It stayed up like this while the special [[Disappearing Sunday Update]] came out on Sunday 2019-08-04, and was there still on Monday [ http://web.archive.org/web/20190805050812/https://www.xkcd.com/ 2019-08-05], at least during the time that the Sudan Update was still up.
**When the next comic came out late that Monday, it probably disappeared along with the Disappearing comic, but the first update with the next header is from Tuesday [http://web.archive.org/web/20190806052948/https://xkcd.com/ 2019-08-06], but the Monday comic [[2185: Cumulonimbus]] was still on the front page at that time,.

===2019-07-23 - Back to previous header===
*[http://web.archive.org/web/20190723205152/https://xkcd.com/ 2019-07-23].
**[[2179: NWS Warnings]] was up when the header changed.
*It returned to the previous header from before the ComicCon header, see [[#2019-07-10 - Adding links|2019-07-10]]
*It stayed up until [http://web.archive.org/web/20190802192259/https://xkcd.com/ 2019-08-02] while [[2184: Unpopular Opinions]] was up. The day after when it changed that comic was still up.

===2019-07-15 - ComiCon===
*[http://web.archive.org/web/20190715181016/http://xkcd.com/ 2019-07-15].
**[[2176: How Hacking Works]] was up when the header changed.
*Randall tells that he will be at ComicCon and links to his plans there.
**The text:
***Going to San Diego Comic Con this week? I'll [https://blog.xkcd.com/2019/07/15/san-diego-comic-con/ see you there]!
****The link is to a [[Blag]] post about his plans for the ComicCon
**Randall appeared in a couple of panels, and gave a talk.
**Finally he also handed out signed copies of his new [[How To]] book more than a month before official release.
***So still promoting the book, also in this header...
*It stayed up until [http://web.archive.org/web/20190722192637/https://www.xkcd.com/ 2019-07-22] the day after the ComiCon ended, while [[2178: Expiration Date High Score]] was up.
**Then it returned to the previous header from before the ComicCon announcement when [[2179: NWS Warnings]] came out.

===2019-07-10 - Adding links===
*[http://web.archive.org/web/20190710165920/https://xkcd.com/ 2019-07-10].
**[[2173: Trained a Neural Net]] was still up when the header changed slightly from that fro the day before.
**Only change was that beneath the picture, see [[#2019-07-09 - Drawings from How To|2019-07-09]], there is now a list of four links to companies where the book can be preordered.
**The extra text:
***[Four links in gray blue are given with the first word in black:] Preorder:[https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 Barnes & Noble],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound],[https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple Books]
*Note that the day after this change, [https://web.archive.org/web/20190711172451/https://xkcd.com/ 2019-07-11], a link to [[How To]] was added to the [[Design_of_xkcd.com#xkcd_links|links]] in the top left corner of xkcd.
*The header stayed like this until [http://web.archive.org/web/20190714175710/https://xkcd.com/ 2019-07-14] when [[2175: Flag Interpretation]] was up. When it changed the day after [[2176: How Hacking Works]] was up.

===2019-07-09 - Drawings from How To===
*[http://web.archive.org/web/20190709162102/https://xkcd.com/ 2019-07-09].
**[[2173: Trained a Neural Net]] was up when the header changed.
**Randall continues to promote his new book, [[How To]].
***The image shows a small picture of his book with text on either side.
***Below are what appears to be three drawings from the book. [[Ponytail]] pole vaultig with three baloons in one hand, then text, then a truck with a house behind it speeding fast up a hill then text and finally [[Cueball]] somersaulting towards an explosion.
***To the right there is a big blue button to click for preorder, with text below.
**The text:
***New book [Arrow points to book. Title can be read: How To]
***How To: Absurd Scientific Answers to Common Real-world Problems
***It's a guide to bad ways to do things...
***...And what would happen if you tried them.
***''Boom''
***Click here to preorder
***Or click anywhere. I still haven't figured out HTML imagemaps.
****The entire picture is a [https://xkcd.com/how-to/ link] to the official [[How To]] page on xkcd: https://xkcd.com/how-to/
****See [[1572: xkcd Survey]] where Randall mentions that he cannot make imagemaps.
*It stayed up like this only for a day, then an extra line of links was added the day after while the same comic was still up, see [[#2019-07-10 - Adding links|2019-07-10]].
**But the general header stayed up first for five days, and then it returned again for 10 more days after a break to announce a [[#2019-07-15 - ComiCon|ComiCon visit]].
**So a total of 16 days with this drawing.

===2019-06-25 - People with books===
*[http://web.archive.org/web/20190625190843/https://xkcd.com/ 2019-06-25].
**[[2167: Motivated Reasoning Olympics]] was up when the header changed.
**Randall continues to promote his new book, [[How To]], and his book tour.
***The image now shows 15 people standing side by side each holding a book up in front of them with unreadable titles.
***From left: [[Megan]], [[Cueball]], a man with blonde hair, [[Jill]], [[Blondie]], [[Hairy]], another Hairy, [[White Hat]], a kid with curly hair, [[Hairbun]], another Cueball, another Megan, a guy with a knit cap, [[Ponytail]], and [[Beret Guy]].
***Above them is a text message.
**The text:
***Want to bring me to your town for my '''''How To''''' book tour? Click to find out how to enter the challenge!
****The entire picture is a [https://blog.xkcd.com/2019/06/10/book-tour-announcement/ link] to the official book tour announcement posted on the [[Blag]], with all cities and dates listed with details.
****In the link it is explained how to enter a competition on how to bring Randall to your city.
****Make a story using only book titles and get the books used to be held up by different individuals.
****A longer sentence will improve your chances.
*****This is indeed what this header picture shows.
*The header stayed like this until [http://web.archive.org/web/20190708155517/https://xkcd.com/ 2019-07-08] when [[2172: Lunar Cycles]] was up. When it changed the day after [[2173: Trained a Neural Net]] was up.

===2019-06-15 - Adding dates===
*[http://web.archive.org/web/20190615100645/http://xkcd.com/ 2019-06-15]
**[[2163: Chernobyl]] was up when the header changed.
**Randall only made a small change to the one that had been up for four days at this time.
**The text only changed by adding a line below the first line:
***Announcing the '''''How To''''' book tour:
***[Click here for dates and tickets]
****The rest of the header is exactly the same as on [[#2019-06-11 - Book tour|2019-06-11]], except everything is a bit smaller to make room in the same place for the extra line.
****The link is not located on the blue part of the text and it was already there before this update.
****Best guess is that not many clicked through and Randall then made it obvious that there was a link.
****The entire picture is a [https://blog.xkcd.com/2019/06/10/book-tour-announcement/ link] to the official book tour announcement posted on the [[Blag]], with all cities and dates listed with details.
****Randall has previously made it clear, in [[1572: xkcd Survey]], that he knows how to make an image a link, but not how to put the link only where he says to click. But it is easier to make a place for people to click than tell them this...
*The header stayed like this until 2019-06-25, when it changed while [[2167: Motivated Reasoning Olympics]] was up. But this one was still up when that comic came out the day before [http://web.archive.org/web/20190624162740/https://xkcd.com/ 2019-06-24].

===2019-06-11 - Book tour===
*[http://web.archive.org/web/20190611031920/https://xkcd.com/ 2019-06-11]
**[[2161: An Apple a Day]] was up when the header changed.
***'''Note''' when this change happened two new links was added to the [[Design_of_xkcd.com#xkcd_links|xkcd links]] section of xkcd.
**Randall changed the header text to announce the official book tour for his newest book ''[[How To]]'' to be released 3 months later.
**The text:
***Announcing the '''''How To''''' book tour:
***[Below this header is a map of the mainland USA with 14 labeled black dots indicates the 14 cities that the book tour will take Randall to. One red dot with five red question marks above is located beneath the map to the left, indicating a 15th city to be chosen in a contest. Above the map to the right is a small picture of the book with the blue title on the black cover. Above the book is the release date and with an arrow pointing down to the book.]
***September 3rd
***How to
***Seattle
***Portland
***San Francisco
***Santa Cruz
***Los Angeles
***Salt Lake City
***Kansas City
***Ann Arbor
***Cincinnati
***Louisville
***Cambridge
***New York
***D.C.
***Raleigh
***????? (Chosen by readers)
***[The entire picture is a [https://blog.xkcd.com/2019/06/10/book-tour-announcement/ link] to the official book tour announcement posted on the [[Blag]], with all cities and dates listed with details.]
****In the link it is explained how to enter a competition on how to bring Randall to your city.
****Make a story using only book titles and get the books used to be held up by different individuals.
****Only US cities can apply.
**The header only stayed exactly like this for three days, and was still up on [http://web.archive.org/web/20190614094729/https://xkcd.com/ 2019-06-14] when [[2162: Literary Opinions]] was on the front page.
***Then it changed slightly to indicate that the picture was a link which was not clear before. See above.

===2019-05-17 - Back to previous header===
*[http://web.archive.org/web/20190517103928/https://xkcd.com/ 2019-05-17]:
**[[2150: XKeyboarCD]] was still up when the header changed.
*It changed back to the exact same heading as before the one with Google reader here below.
**See [[#2019-02-06 - How to book|2019-02-06]] below for all details.
**It stayed up for more than three weeks and was still up on [http://web.archive.org/web/20190610055519/https://www.xkcd.com/ 2019-06-10], while [[2160: Ken Burns Theory]] was still up on the day the next comic [[2161: An Apple a Day]] was to be released (where the new header could be found at least the next day, but maybe from the release of that comic?). Then it changed to announce the book tour for his new book.

===2019-04-23 - Google Reader===
*[http://web.archive.org/web/20190423155458/https://xkcd.com/ 2019-04-23]:
**[[2140: Reinvent the Wheel]] came out when it changed, ending a more than two and half month long [[#2019-02-06 - How to book|promotion]] of Randall's new book [[How To]].
**Randall changed the header text to ask if the reader still mourned the loss of {{w|Google Reader}} which closed on 2013-07-01, almost 6 years before this comic..
***He offers the possibility to sign up to receive the newest comic by e-mail.
**The comic may have relation to this, as some where using Google reader for different purposes when they closed it, without any chance of [https://www.google.com/reader/about/ getting your data out].
***The comic "Reinvent the Wheel" mentions that using external dependencies carry risks, such as Google closing down a feature. given the fact that the comic came out as the header changed it is probably not a coincidence.
**The text:
***Still mourning the demise of Google Reader? You can sign up to get new comics delivered by email [https://xkcd.com/newsletter/ here].
**The link is to https://xkcd.com/newsletter, where it is possible to submit your e-mail address and press a subscribe button.
***the following text is written above it:
***To receive the comic and news postings in your inbox, subscribe here.
**It stayed up for more than three weeks and was still up on [http://web.archive.org/web/20190516100403/https://xkcd.com/ 2019-05-16], when [[2150: XKeyboarCD]] was up. Then it changed back to the promotion of his new book.

===2019-02-06 - How to book===
*[http://web.archive.org/web/20190206060904/https://xkcd.com/ 2019-02-06]:
**[[2107: Launch Risk]] was up at the time when it changed, having been up since Monday the 4th of February.
***Here it can be seen being on the front of xkcd on [http://web.archive.org/web/20190205050302/https://xkcd.com/ 2019-02-05], without the new text. This was also the last time the standard header text was used in several months.
***[[2108: Carbonated Beverage Language Map]] came up later on the day the header changed.
**Randall changed the header text to promote his newest book ''[[How To]]'' to be released 7 months later.
***He added an image of the book with large text next to it regarding the release and links on how to preorder it.
***There was no direct relation to the comics released at the time, except of course that he kind of launched his new book with all the risk it involves, while having a comic called launch risk up. It was though a very different and more real type of launch risk (of a human carrying space rocket) in the comic.
**The text:
***[The book is shown to the left as a black rectangle with large blue text and smaller gray text. On the book cover, in white drawings, are seen Megan with a ladder and either Black or White Hat (hard to say on black background). Both are looking up on Cueball who is floating in the air with a quadcopter beneath either leg, trying to plug in an electric light bulb in a naked lamp hanging down near him. It seems he has already removed the broken light bulb, as he has one in both hands. And now he tries to put in the new one. He could have let Megan use the ladder...]
***[The header in blue above it all:] How To.
***[Sub header in gray to the left of Cueball:] Absurd Scientific Answers to Common Real-world Problems
***[Author name in blue below the drawing:] Randall Munroe
***[Sub header to this below in gray:] Creator of xkcd
***[Sub header to this below in gray:] Author of what if? and Thing Explainer
***[Next to this book image are the following text:]
***[Large heading:] HOW TO
***[Normal size sub header:] Absurd Scientific Answers to Common Real-world Problems
***[In smaller gray font below:] Available September 3, 2019.
***[Four links in gray blue are given with the first word still in gray:] Preorder:[https://www.amazon.com/How-Absurd-Scientific-Real-World-Problems/dp/0525537090/ Amazon],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/2/trackingcode/PRH5522E62429 Barnes & Noble],[http://links.penguinrandomhouse.com/type/affiliate/isbn/9780525537090/siteID/8001/retailerid/6/trackingcode/penguinrandom IndieBound],[https://itunes.apple.com/us/book/how-to/id1451461524?mt=11 Apple Books]
**It stayed up for more than two and a half month and was still up on [http://web.archive.org/web/20190422030324/https://xkcd.com/ 2019-04-22], when [[2139: Email Settings]] was up. Then it finally changed to a new header without going back to the standard.

===2018-11-07 - Back to standard text===
*[http://web.archive.org/web/20181107144453/https://www.xkcd.com/ 2018-11-07]
**The text returned to the standard xkcd header:
***xkcd updates every Monday, Wednesday, and Friday.
**It stayed like this until [[2107: Launch Risk]] was up on [http://web.archive.org/web/20190205050302/https://xkcd.com/ 2019-02-05], so two days less than three months.
***After this it did not return to the standard text for almost three years, but just short of a month before the third year without it, it returned on [[#2022-01-08 - Back to standard text|2022-01-08]].

===2018-11-06 - Election Day===
*[http://web.archive.org/web/20181106122850/https://xkcd.com/ 2018-11-06]:
**[[2068: Election Night]] (on election day the day after this comic was released).
***It added a larger comic above the two links from the previous header. Those links of the previous header text was still up the day before [http://web.archive.org/web/20181105105855/https://xkcd.com/ 2018-11-05], when [[2067: Challengers]] was still up.
**Randall changed the xkcd header once more to try to make more people vote, and in this case help others to vote.
***Once again directly related to the new comic about election night.
**The text:
***[A line of altering blue and red stars, blue first and last of two rows of nine starts around of the heading:]
***Election Day!
***[Below Black Hat and Ponytail to the left and Megan to the right of Cueball is checking their smart phones. Cueball is addressing the reader:]
***Cueball: The biggest thing you can do th help is to check in with friends and family and make sure they know when and where they're voting.
***[Below these four characters there is the following text with two arrows pointing left and right. Both are turning up to text/links on either side of the four:]
***Use these links to answer questions
***[To the left:] Where and how to vote: [https://www.vote.org/ Vote-org]
***[To the right:] What's on your ballot: [https://www.ballotready.org/ BallotReady.org]
***[Below was the two links from the previous header:]
***Find out where to vote: [https://www.vote.org/ vote.org].
***See what's on your ballot: [https://www.ballotready.org/ BallotReady.org]
**It was only up one day and thus on ended the day after [http://web.archive.org/web/20181107144453/https://www.xkcd.com/ 2018-11-07] when the next comic [[2069: Wishlist]] came out.
***The text then returned to the standard xkcd header: xkcd updates every Monday, Wednesday, and Friday.
****It stayed like this until [[2107: Launch Risk]] was up on [http://web.archive.org/web/20190205050302/https://xkcd.com/ 2019-02-05].

===2018-11-02 - Where to vote===
*[http://web.archive.org/web/20181103021059/https://xkcd.com/ 2018-11-02]:
**[[2067: Challengers]] (on the Friday, it was released).
***It added another link to the previous header text. That text was still up the day before on Thursday [http://web.archive.org/web/20181102015102/https://xkcd.com/ 2018-11-01].
***That was while comic [[2066: Ballot Selfies]] was still up.
**Randall changed the xkcd header to let people know who is on their voting ballot, and as before there is also a link on how to register for voting.
***This is also directly related to the new comic that came out that day, about helping people to decide who to vote for, i.e. who is on their ballot.
**The text:
***Find out where to vote: [https://www.vote.org/ vote.org].
***See what's on your ballot: [https://www.ballotready.org/ BallotReady.org]
**This was done at this moment because the {{w|United States midterm election}} was held on {{w|United States elections, 2018|Tuesday, November 6, 2018}}, four days after the release of this comic.
**It was still up the day before the election day, [http://web.archive.org/web/20181105105855/https://xkcd.com/ 2018-11-05], and then it changed with the next comic.

===2018-10-22 - Register for voting===
*[http://web.archive.org/web/20181022120935/https://xkcd.com/ 2018-10-22]:
**[[2061: Tectonics Game]] (on a Monday, the 3rd day after release of this Friday comic)
***The standard text was still up Sunday [http://web.archive.org/web/20181021141446/https://xkcd.com/ 2018-10-21].
***The comic [[2062: Barnard's Star]] was released later that day.
**Randall changed the xkcd header to try to get people to register for voting.
**The text:
***Check your registration and find your polling place at [https://www.vote.org/ vote.org].
**This was done at this moment because the {{w|United States midterm election}} was held on {{w|United States elections, 2018|Tuesday, November 6, 2018}}, about two weeks after the release of this comic.
***It is generally believed that many of those not voting would have chosen democrats on election day, and thus Randall has an interest in getting as many as possible to register, see [[1756: I'm With Her]] (apart from the fact that he also most likely thinks that it is important to use the right to vote).
**It ended on [http://web.archive.org/web/20181103021059/https://xkcd.com/ 2018-11-02], when [[2067: Challengers]] came out.
***It was still there while [[2066: Ballot Selfies]] was still up the day before on [http://web.archive.org/web/20181102015102/https://xkcd.com/ 2018-11-01].

===2018-09-13 - NY votes today===
*[http://web.archive.org/web/20180913133544/https://xkcd.com/ 2018-09-13]
**[[2045: Social Media Announcement]] (the day after the release of the comic.)
***It was not up when the comic was released on [http://web.archive.org/web/20180912131437/https://xkcd.com/ 2018-09-12].
**It was a short lived reminder that NY votes today below the usual standard text.
**The text:
***xkcd updates every Monday, Wednesday, and Friday.
***NY votes today! Find your polling place [https://voterlookup.elections.ny.gov/ here]. (Zephyr Teachout for AG!)
**It ended with [[2046: Trum-]], the very next comic, on [http://web.archive.org/web/20180914175605/https://xkcd.com/ 2018-09-14], returning to the standard text.

===2017-11-26 - Christmas gifts===
*[http://web.archive.org/web/20171126130857/http://xkcd.com/ 2017-11-26]
**[[1920: Emoji Sports]] had been up two days [http://web.archive.org/web/20171125125648/https://xkcd.com/ 2017-11-25] before the message changed from the normal version. But it changed the day before the next comic came up.
***It was changed to a commercial for Christmas shopping with a code for getting 5$ of the price with a codes for different online shops.
**The text:
***To anyone looking for Christmas gifts: Until Monday you can get $5 off
***[https://www.amazon.com/What-International-Scientific-Hypothetical-Questions/dp/0544456866 What If?] and [https://www.amazon.com/Thing-Explainer-Complicated-Stuff-Simple/dp/0544668251 Thing Explainer] on Amazon with coupon code GIFTBOOK17.
***At Barnes & Noble, until Sunday you can get 20% off [https://www.barnesandnoble.com/w/what-if-serious-scientific-answers-to-absurd-hypothetical-questions-randall-munroe/1118864093 What If?] and [https://www.barnesandnoble.com/w/thing-explainer-randall-munroe/1121864432 Thing Explainer] using code GIVETHANKS.
**It was only up a few days and ended with [[1922: Interferometry]] on [http://web.archive.org/web/20171130150053/http://xkcd.com/ 2017-11-30] where it returned to the standard text.
***But it was still up when the comic in between [[1921: The Moon and the Great Wall]] was up on [http://web.archive.org/web/20171129140033/http://xkcd.com/ 2017-11-29].

===2017-09-22 - Visiting the UK===
*[http://web.archive.org/web/20170922232616/https://xkcd.com/ 2017-09-22]:
**[[1893: Thread]] (with its release).
***It was not up on the previous comic [[1892: USB Cables]], on the day they changed [http://web.archive.org/web/20170922025204/https://xkcd.com/ 2017-09-22].
**It was an announcement that Randall would visit the UK next week.
**The text:
***I'll be visiting the UK next week! You can join me in London from September 30-October 2 (at [https://live.newscientist.com/speakers/randall-munroe New Scientist Live], [http://www.rigb.org/whats-on/events-2017/october/public-lunchtime-talk--randall-munroe The Royal Institution], and [http://www.intelligencesquared.com/events/randall-munroe-on-making-complicated-stuff-simple/ Intelligence Squared]), then from October 3-6 in [https://www.stpetersyork.org.uk/public_lectures/randall_munroe_thing_explainer York], [https://www.eventbrite.co.uk/e/thing-explaining-with-randall-munroe-tickets-37832289396 Edinburgh], [https://www.toppingbooks.co.uk/events/ely/randall-murray-thing-explainer/ Cambridge and Ely], [https://www.eventbrite.co.uk/e/randall-munroe-book-signing-thing-explainer-tickets-38041072873 Oxford], and [http://www.cheltenhamfestivals.com/literature/whats-on/2017/randall-munroe/ Cheltenham].
**Ended with [[1900: Jet Lag]] on [http://web.archive.org/web/20171010045802/https://xkcd.com/ 2017-10-10] when the text returned to normal.
***But it was still up the day before with [[1899: Ears]] on [http://web.archive.org/web/20171009040109/https://xkcd.com/ 2017-10-09].

===2017-07-31 - Thank you===
*[http://web.archive.org/web/20170731021227/https://www.xkcd.com/ 2017-07-31]:
**[[1869: Positive and Negative Reviews]] (3rd day after release of this Friday comic)
***The comic [[1870: Emoji Movie Reviews]] was released later that day.
***Megan is holding hand with Cueball and next to them is two words above each other: Thank you.
***The image is also a link.
****The link goes to [http://web.archive.org/web/20170801042453/https://www.nytimes.com/interactive/2017/07/25/us/politics/senate-votes-repeal-obamacare.html How Each Senator Voted on Obamacare Repeal Proposals], an article showing the senate votes. (here in an archived version).
**Ended with [[1872: Backup Batteries]] on [http://web.archive.org/web/20170804152509/https://xkcd.com/ 2017-08-04], but was still up when [[1871: Bun Alert]] was up on [http://web.archive.org/web/20170803124342/https://xkcd.com/ 2017-08-03].

===2017-07-25 - Vote against health care bill===
*[http://web.archive.org/web/20170725103104/https://xkcd.com/ 2017-07-25]:
**[[1867: Physics Confession]] (2nd day after release of the comic, it was not up on the first day: [http://web.archive.org/web/20170724095252/https://xkcd.com/ 2017-07-24]).
**Randall modified the xkcd header to ask readers to support voting against Donald Trump's new health care bill.
***The header was replaced with an image which is available in an archived version [https://web.archive.org/web/20170726150959im_/https://imgs.xkcd.com/notes/call-senate.png here].
***The image is also a link (and you can click anywhere on it to go to the link that is mentioned).
****The link goes to [http://web.archive.org/web/20170729003307/https://www.trumpcareten.org/daily TrumpCare Ten] (here in an archived version).
****Randall has previously made it clear, in [[1572: xkcd Survey]], that he knows how to make an image a link, but not how to put the link only where he says to click.
***Transcript of the image:
****[Megan is holding hand with Cueball next to three lines of large text, the same height as they are:]
****Please tell your senators to vote against this health care bill. It will hurt people.
****[After these three lines there is a phone number in a very large bold font with a line of text below:]
****202-224-3121
****Or click here for more info
****[Below the above is a gray line which is split in the middle with gray text, and below that four state names in white text inside black boxes:]
****Know anyone in these states? Ask them to call, too.
****Alaska Maine Nevada Ohio West Virginia
**Ended while [[1869: Positive and Negative Reviews]] was up on [http://web.archive.org/web/20170731164828/https://xkcd.com/ 2017-07-31], when it was replaced by a ''Thank you''.
***That comic came out already [http://web.archive.org/web/20170728124230/https://xkcd.com/ three days before] (Friday comic), but was still up on [http://web.archive.org/web/20170730141019/https://www.xkcd.com/ 2017-07-30]) when the message changed sometimes between Sunday 30th and Monday 31st (where [[1870: Emoji Movie Reviews]] was released).

===2017-01-21 - Update on previous===
*[http://web.archive.org/web/20170122003124/https://xkcd.com/ 2017-01-21]:
**[[1788: Barge]]
**It came up almost a month after Christmas but did not really change the sales pitch of the previous. It just removed the link image with the large red text, see previous version below.
**The text:
***There are [https://store.xkcd.com/collections/featured four new shirts] in [https://store.xkcd.com/ the xkcd store],
***along with [https://store.xkcd.com/collections/posters posters] and [https://store.xkcd.com/collections/everything lots of other stuff]!
**Ended with [[1867: Physics Confession]] on [http://web.archive.org/web/20170725103104/https://xkcd.com/ 2017-07-25].
***That comic came up [http://web.archive.org/web/20170724095252/https://xkcd.com/ the day before] the above version of the header appeared.
***So the first day after release it was still the T-shirt commercial.
***And it did not return to the standard version in between.

===2016-11-28 - Christmas sale===
*[http://web.archive.org/web/20161128153015/http://xkcd.com 2016-11-28]
**[[1765: Baby Post]]
**This came up in time for the Christmas sale of 2016.
**The text was
***There are [https://store.xkcd.com/collections/featured four new shirts] in [https://store.xkcd.com/ the xkcd store],
***along with [https://store.xkcd.com/collections/posters posters] and [https://store.xkcd.com/collections/everything lots of other stuff]!
***Above the text there was an image with two black t-shirts with white print on the chest. They were located at either end of a large red text written in the text type used in the comic. This text said New xkcd shirts.
***The entire image was a link to the [https://store.xkcd.com/ xkcd store].
**Ended with [[1788: Barge]] [http://web.archive.org/web/20170121114423/https://xkcd.com/ 2017-01-21]

===2016-04-23 - Back to standard text===
*[https://web.archive.org/web/20160423103108/http://xkcd.com/ 2016-04-23]
**When [[1671: Arcane Bullshit]] came out (probably 2016-04-22, but no earlier archived versions exist) the text returned to the standard xkcd header:
***xkcd updates every Monday, Wednesday, and Friday.
**It stayed like this for more than 7 months until [[1764: XKCDE]] was up on [https://web.archive.org/web/20161128093459/http://xkcd.com/ 2016-11-28].

===2016-04-04 - Protip on Garden===
*[https://web.archive.org/web/20160404185353/http://www.xkcd.com/#5dbfbb82-fc20-11e5-8001-42010a8e000d 2016-04-04]
**Because of the complexity of the [[:Category:April fools' comics|April fools' comic]] [[1663: Garden]], Randall needed to give people some advice, hence a [[:Category:Protip|protip]] was added.
***This came in several versions, not all managed to be documented in the archive. See more in the trivia for garden regarding the [[1663:_Garden#Header_text_after_release|Header text after release]].
**The header text became a protip with the following text (the first version not documented only had the first line):
***'''Protip''': If you don't like how your garden is growing, you can click to prune it.
***You can copy the URL to share your garden. From other browsers, it will be view-only.
**When the next comic, [[1664: Mycology]], was released two days later on [https://web.archive.org/web/20160406194653/http://xkcd.com/1664/ 2016-04-06], an extra line of text was added, due to the issues caused by Garden not being on the front page {{xkcd}} but only on the numbered page {{xkcd|1663}}.
***This change was first documented on the front page the day after on [https://web.archive.org/web/20160407010635/http://xkcd.com/ 2016-04-07]
***The change was of course also on and all the other comic and thus also on the Garden comic from [https://web.archive.org/web/20160406192530/http://xkcd.com/1663/ 2016-04-06].
**Text added below the other two lines:
***Note: If you're seeing today's comic in place of your garden, change the URL from xkcd.com/#<your code> to xkcd.com/1663/#<your code>.
****This extra line was only there until next time the comic change, so last day was [https://web.archive.org/web/20160408145017/http://xkcd.com/ 2016-04-08].
**On [https://web.archive.org/web/20160408195958/http://xkcd.com/ 2016-04-08] when [[1665: City Talk Pages]] was released the extra line was removed leaving the two written first here above.
***This was also the case on the Garden comic (and all other comics) from [https://web.archive.org/web/20160408204740/http://xkcd.com:80/1663/ 2016-04-08].
**The Protip stayed in the main header text until [https://web.archive.org/web/20160422102754/http://xkcd.com/ 2016-04-22] when [[1670: Laws of Physics]] was up.
***But even though it disappeared from main header and thus from all other comic it stayed on the Garden comic, also on [https://web.archive.org/web/20160423182630/http://xkcd.com:80/1663/ 2016-04-23].
***And it has then turned out to become one of the permanent [[xkcd_Header_text#Garden|Unique header texts]].

===2016-04-04 - Back to standard text as Garden came up===
*[https://web.archive.org/web/20160404123555/http://xkcd.com/ 2016-04-04]
**For a brief period of time, when [[1663: Garden]] was finally released, the Header text returned to the standard xkcd header:
***xkcd updates every Monday, Wednesday, and Friday.
**But this lasted less than 13 hours. (Time between the previous and next archived version is 13 hours and 7 minutes).
***As people needed guidance to the new complicated comic.

===2016-04-01 - April 1st comic - technical difficulties===
*[https://web.archive.org/web/20160401204749/https://xkcd.com/ 2016-04-01]
**When Randall had problem releasing [[1663: Garden]] several [[1663:_Garden#April_Fools.27_header_text|April Fools' header text]] arrived in short succession while [[1662: Jack and Jill]] was still up.
**Each of these where simple text.
***The first from the link abve:
****The xkcd April 1st comic is currently experiencing technical difficulties.
****Please stand by!
***The next from [https://web.archive.org/web/20160402125723/http://xkcd.com:80/ 2016-04-02] at 12:57:
****The xkcd April 1st comic is currently experiencing technical difficulties.
****Status update: Please stand by.
****Status update: This is fine. Everything is fine.
****Status update: Everything is on fire.
****Status update: Searching for calendar systems in which Saturday is April 1st.
***The next from [https://web.archive.org/web/20160402175822/http://www.xkcd.com 2016-04-02] at 17:58:
****The Friday xkcd comic is currently experiencing technical difficulties
****[Editor's note: Everything is on fire] and has been delayed until Sunday night.
**It stayed like the third version until [https://web.archive.org/web/20160404054612/http://xkcd.com/ 2016-04-04] three days after the April Fools' comic was supposed to come out, so Jack and Jill was up until it changed.
*This was what was needed to stop more than 10 months of promotion of the [[Thing Explainer]] book, see below.

===2015-12-13 - Thing Explainer is available===
*[https://web.archive.org/web/20151213194534/http://xkcd.com/ 2015-12-13]
**[[1615: Red Car]] was still up when the header changed.
***The change was that the promotion for where Randall was last week where removed and left only the promotion the book [[Thing Explainer]]:
**The text:
***Thing Explainer is available at: [https://www.amazon.com/Thing-Explainer-Complicated-Stuff-Simple/dp/0544668251 Amazon], [https://www.barnesandnoble.com/w/thing-explainer-randall-munroe/1121864432?ean=9780544668256#/ Barnes & Noble], [https://www.indiebound.org/book/9780544668256 Indie Bound], [https://www.hudsonbooksellers.com/thingexplainer Hudson]
**It was last up on [https://web.archive.org/web/20160401125621/http://xkcd.com/ 2016-04-01] while [[1662: Jack and Jill]] was on the front page.
***This was the last time that Thing Explainer was [[:Category:Book promotion|promoted]] in the header text.
****The first time was [[xkcd_Header_text#2015-05-14_-_New_book_Thing_Explainer|2015-05-14]], so it had been part of the header text for almost ten and a half month. That is a record!

===2015-12-05 - Thing Explainer is available and Next week===
*[https://web.archive.org/web/20151205070539/http://xkcd.com/ 2015-12-05]
**[[1612: Colds]] was up when the header changed.
***This was also at this time the [[2015-11-24 - Pages from my new book Thing Explainer|previous header texts image] was moved below the comic.
**Randall goes back to a simple promotion of the book [[Thing Explainer]] listing where to boy it.'
***But he adds a line about where he will be next week, first to a book shop on Illinois and then later in Toronto, where the host was {{w|Ryan North}} from [https://qwantz.com/ Dinosaur comics], one of the [[Design_of_xkcd.com#Comics_I_enjoy|comics Randall enjoys]].
**The text:
***Thing Explainer is available at: [https://www.amazon.com/Thing-Explainer-Complicated-Stuff-Simple/dp/0544668251 Amazon], [https://www.barnesandnoble.com/w/thing-explainer-randall-munroe/1121864432?ean=9780544668256#/ Barnes & Noble], [https://www.indiebound.org/book/9780544668256 Indie Bound], [https://www.hudsonbooksellers.com/thingexplainer Hudson]
***I'll be in [https://web.archive.org/web/20151211002159/http://www.andersonsbookshop.com/event/naperville-reads-randall-munroe Naperville, IL] and [https://web.archive.org/web/20151205205714/http://www.eventbrite.ca/e/indigo-exclusive-randall-munroe-tickets-18694384407 Toronto, ON] (with [https://qwantz.com/ Ryan North]!) next week.
**It was last up on [https://web.archive.org/web/20151212133400/http://xkcd.com:80/ 2015-12-12] while [[1615: Red Car]] was on the front page.

===2015-11-24 - Pages from my new book Thing Explainer===
*[https://web.archive.org/web/20151203234149/http://xkcd.com/ 2015-12-03]
**[[1611: Baking Soda and Vinegar]] was still up when the header changed.
***This was a special one comic header text consisting of a large image with pages and excerpts from the book [[Thing Explainer]].
***The image was larger than most comics, and took away the focus of today's comic.
***So already two days after, when [[1612: Colds]] was released, the image was relegated to the being below the comic, but inside the [[Design_of_xkcd.com#Main_comic|main comic]] segment, thus not a part of the [[Design_of_xkcd.com#Bottom_segment|bottom segment]].
****But it was displayed in the header for all comics, here [https://web.archive.org/web/20151204030024/http://xkcd.com/1609/ an example] from the comic released two comics before 1611, [[1609: Food Combinations]].
****See more (and the image) [[Thing_Explainer#Promotion_at_the_xkcd_home_page|here]] on the page for Thing Explainer.
**Description of the image:
***At the top are shown four pages from the book. Two mainly blue, left and right, with white text and large images and between them two mainly white pages with blue text and smaller images. None of the text is readable, but the two blue pages pictures can be understood even in this size.
****The first page is number 2 about an animal cell: ''Tiny bags of water you’re made of''. It shows a detailed drawing of a human cell, with text at the top, and then several labels with text beneath that have arrows pointing to different parts of the cell.
****The second page is number 31 about the cockpit of an airplane: ''Stuff you touch to fly a sky boat''. It shows the inside of a cockpit with view out of the four windows, with lots of buttons in the ceiling, and blue screens and instruments at the bottom. Out the windows can be seen clouds and Cueball hanging from a balloon (a reference to [[1110: Click and Drag]]).
*****A zoom in on this page is shown beneath the four pages, see more below.
****The third page is page 27. What is on this page is a bit difficult to see, as there are no big drawings with clear meaning. It is the second page in a two page section on Data centers, with the second page focusing on the Computer: ''Computer building''. The pictures shows the data racks, to the right, and the individual computer components put into these, to the top left, with the wiring shown below to the left. Lots of text with arrows to different parts.
****The fourth page is page 23 about Trees: ''Tree''. It clearly shows the silhouette of a white tree on blue background. Several animal live on, in and beneath it. Cueball is standing on the ground. All the text are beneath labels that points to parts of the tree or the tree dwellers.
***In between the two time two pages there is a readable text, split over five lines, with two arrow at the top going from the corners of the text to the near corners of the white pages to either side. And below three arrows, with two pointing similarly as the two top arrows, but starting at the bottom of the text, and one arrow pointing straight down from the middle of the text to the large image below.
***Beneath all this is a large image which shows a zoom in on the left part of the cockpit from the second page above. The zoom is focused on the two front windows, but only the left is entirely in the picture, and the balloon hanging Cueball, cannot be seen in this part of the right window.
****At this zoom level, most of the text van be read (that is labels written on things or having arrows pointing to them). Clouds can bee seen out of both windows and in the background a rocket launch with smoke plume below the rocket is visible. The horizon line is well defines across both windows. Some of the instruments can be seen below the windows with text written on them. And some blue areas, mainly screens can be seen.
***Beneath this picture is a line with links to where the book can be ordered, like the one from the previous header text.
**The text:
***Pages from my new book, ''Thing Explainer'': Complicated stuff in simple words.
***[Labels in the cockpit]:
****Sky
****Ground (This should be below the sky. If it's above the sky, you're either having a big problem or doing something ''really'' fun.)
****Use this stuff to tell the sky boat to fly itself.
****Fly
****How fast it feels IAS 172
****Direction HDG 240
****Fall or rise
****How high 2500
****Fly
****Helpful screen
****Where the ground is
****You are: Flying
****Look here if there is a problem
***Below this image is a line of text with the first word in black and the other are four links to where to order the book:
****Order: [https://www.amazon.com/Thing-Explainer-Complicated-Stuff-Simple/dp/0544668251 Amazon], [https://www.barnesandnoble.com/w/thing-explainer-randall-munroe/1121864432?ean=9780544668256#/ Barnes & Noble], [https://www.indiebound.org/book/9780544668256 Indie Bound], [https://www.hudsonbooksellers.com/thingexplainer Hudson]
***The image is a link to [https://www.amazon.com/gp/product/0544668251/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0544668251&linkCode=as2&tag=thekcs-20&linkId=S4XRZJJKSMHOWEQU Thing Explainer on Amazon].
**It was only part of the header for two days until [https://web.archive.org/web/20151204050419/http://xkcd.com/ 2015-12-04].
***It was then moved below the comics as mentioned above from [https://web.archive.org/web/20151205070539/http://xkcd.com/ 2015-12-05] when the next comic [[1612: Colds]] came out.

===2015-11-24 - Thing Explainer is out today===
*[https://web.archive.org/web/20151124201602/http://xkcd.com/ 2015-11-24]
**[[1607: Supreme Court]] was still up, but [[1608: Hoverboard]] most have come out close to the change.
***See both [https://web.archive.org/web/20151125001228/http://xkcd.com/ 2015-11-25 00:12] and [https://web.archive.org/web/20151125230753/http://xkcd.com/ 2015-11-25 23:07].
***Since this new "comic" was actually a {{w|browser game}} made to celebrate the release of Randall's new book, ''[[Thing Explainer]]'', which was released on the same day as this comic: Tuesday, November 24, 2015. The comic thus appeared on a Tuesday, replacing that week's normal Wednesday release to coincide with the release day.
***Hence it is a shame that there is no archived versions on the 24th showing Hoverboard on the front page. Even though the new version of the Header text is shown on the 24th, but on the previous comic.
**Cause all the header text is about is the release day of Thing Explainer!
***The top part is text with a line with large letters and a line below in brackets and using smaller letters. Below that there is a line dividing the text from the next part.
***Below follows the same header that was up as early as [[#2015-05-15 - Thing Explainer details|2015-05-15]] with the open book and three lines of text.
**The text:
***My new book, [http://blog.xkcd.com/2015/05/13/new-book-thing-explainer/ Thing Explainer], is out today!
***(If you're in NYC, you can also [https://web.archive.org/web/20150925015809/http://stores.barnesandnoble.com:80/author/11170358 come see me]!)
***A picture of the open book is shown with diagrams of a human cell on the left page and suspension bridges on the right. All held in blue nuances. And arrow goes from the first word of the text to the right to the book on the left. The text is also blue except the title of the book which is in red:
****New book: Thing Explainer
****Up Goer Five-style diagrams of things (explained in the ten-hundred most common words)
***Below this image is a line of text with the first word in black and the other are four links to where to order the book:
****Order: [https://www.amazon.com/Thing-Explainer-Complicated-Stuff-Simple/dp/0544668251 Amazon], [https://www.barnesandnoble.com/w/thing-explainer-randall-munroe/1121864432?ean=9780544668256#/ Barnes & Noble], [https://www.indiebound.org/book/9780544668256 Indie Bound], [https://www.hudsonbooksellers.com/thingexplainer Hudson]
***The image above the order line is a link to the [[Blag]] post [https://blog.xkcd.com/2015/05/13/new-book-thing-explainer/ New book: Thing Explainer].
**Already the day after [https://web.archive.org/web/20151125001228/http://xkcd.com/ 2015-11-25], when [[1608: Hoverboard]] was up, an extra line (a link) was added below the above. A line was separating it from the links above:
***[http://blog.xkcd.com/2015/11/24/a-puzzle-for-the-uk/ A puzzle for UK readers]
****This was to a blag post with A puzzle for the UK because he could not go to UK in person. So this was a kind of bonus for those who could solve it. (We need an entry on that here on xkcd...)
**On [https://web.archive.org/web/20151127114432/http://xkcd.com/ 2015-11-27] is still looked like this but then when the next comic, [[1609: Food Combinations]], came out on [https://web.archive.org/web/20151128130851/http://xkcd.com/ 2015-11-28] the line about seeing him in New York was removed.
**The version with the puzzle, but without the New York line, was then up until [https://web.archive.org/web/20151201222148/http://xkcd.com/ 2015-12-01] when [[1610: Fire Ants]] was up.
**Then on [https://web.archive.org/web/20151202225254/http://www.xkcd.com/ 2015-12-02] the line with the puzzle at the bottom was changed to:
***I'm doing a [https://www.facebook.com/AndyWeirAuthor/ live Q&A;] at 2:30pm PT with The Martian author Andy Weir.
****The link is to {{w|Andy Weir}}'s Facebook page. And the Q&A can likely not be seen anymore.
****Randall has made no less than two comics about the movie {{w|The Martian (film)|The Martian}}, [[1536: The Martian]] and [[1585: Similarities]].
***It only lasted that day, and this became the last day with this header text, so it ended while [[1611: Baking Soda and Vinegar]] was up.

===2015-10-22 - World Polio Day===
*[https://web.archive.org/web/20151022200022/http://xkcd.com/ 2015-10-22]
**[[1593: Play-By-Play]] was up when the header changed.
***Randall mentions World Polio Day and the comic he drew for Bill Gates' blog, [[XKCD Marks the Spot]].
***Although he still keeps mentioning the release date for [[Thing Explainer]].
**The text:
***We've [https://slate.com/technology/2015/08/no-new-polio-in-africa-for-one-year-gates-epidemiologist-on-vaccines-and-surveillance.html almost eradicated polio]. For World Polio Day, I drew a comic
***about the eradication efforts. You can see it on [https://www.gatesnotes.com/Health/XKCD-Marks-the-Spot Bill Gates's blog].
***My [https://blog.xkcd.com/2015/05/13/new-book-thing-explainer/ new book] of complex diagrams and simple words comes out Nov 24th.
****The last line is split from the Polio announcement with a line.
**Was there until [[1607: Supreme Court]] was up on [https://web.archive.org/web/20151124065108/http://xkcd.com:80/ 2015-11-24].
***That was the day that the book was released, and when the next comic [[1608: Hoverboard]] came out, it was a celebration of the book.

===2015-09-23 - Book trip and tool===
*[https://web.archive.org/web/20150923044724/http://xkcd.com/ 2015-09-23]:
**[[1580: Travel Ghost]] was up when the header changed.
***Announcing the book trip for the [[Thing Explainer]] book as well as linking to a Thing Explainer word checker tool! Two lines of text with links.
**The text:
***News: Announcing my Thing Explainer [https://blog.xkcd.com/2015/09/22/im-going-on-a-book-trip/ book trip]. Come say hi!
***Other news: Announcing the Thing Explainer [https://blog.xkcd.com/2015/09/22/a-thing-explainer-word-checker/ word checker] tool!
****Both links are to the [[Blag]], the first a schedule for his book trip, and the second telling about Randall's new [https://xkcd.com/simplewriter/ Simple Writer] that could help you ''Write Like Up Goer Five and Thing Explainer''.
**Was there until [[1593: Play-By-Play]] was up on [https://web.archive.org/web/20151021164208/http://xkcd.com/ 2015-10-21].

===2015-09-06 - New links===
*[https://web.archive.org/web/20150906181550/http://xkcd.com/ 2015-09-06]:
**[[1573: Cyberintelligence]] was still up when the header changed.
***The promotion of the book, [[Thing Explainer]], stayed the same with a picture above links to preorder it, but the links was reduced from four to two, the amazon link changed and a new company was added for the second link removing the other three.
***See [[#2015-05-15 - Thing Explainer details|2015-05-15]] below for all details on the image.
**The new link text:
***Preorder: [https://www.amazon.co.uk/Thing-Explainer-Randall-Munroe/dp/1473620910 Amazon.co.uk}, [https://www.waterstones.com/book/thing-explainer/9781473620919 Waterstones]
**Was there until [[1579: Tech Loops]] was up on [https://web.archive.org/web/20150919220105/http://xkcd.com/ 2015-09-22].

===2015-08-09 - Back to previous header===
*[https://web.archive.org/web/20150809230825/http://xkcd.com/ 2015-08-09]:
**[[1561: Water Phase Diagram]] was still up when the header changed.
***It changed back to the exact same heading as before the one with other news here below.
****See [[#2015-05-15 - Thing Explainer details|2015-05-15]] below for all details.
**Stayed like this until [[1573: Cyberintelligence]] was out on [https://web.archive.org/web/20150905154014/https://xkcd.com/ 2015-09-05], but the only change was that the links to preorder changed from four to only two.

===2015-06-06 - Other news===
*[https://web.archive.org/web/20150606084120/http://www.xkcd.com/ 2015-06-06]
**Changed while [[1534: Beer]] was still up.
***This was just adding some "Other news", but leaving the promotion of [[Thing Explainer]] unchanged as in the [[#2015-05-15 - Thing Explainer details|previous header]], but adding two news stories in text below the link to preorder.
**The new text:
***In other news, [https://www.youtube.com/watch?v=ygrdAvmr-MA Space Weird Thing] is delightful, and I feel surprisingly invested in [https://web.archive.org/web/20150720074919/https://twitter.com/xkcdbracket @xkcdbracket's] results.
****The link to Space Weird Thing is a YouTube video with a simple words version of {{w|David Bowie|David Bowie's}} [https://www.youtube.com/watch?v=iYYRH4apXDo Space Oddity] music video, using only the top then hundred words. The creators contributes the idea to the [[1133: Up Goer Five]] diagram which also inspired the book Thing Explainer, also promoted in this header text.
****The other link is referring to [[1529: Bracket]] released 12 days before this update, as a twitter user made a survey going through all the brackets all the way to a winner was found. Seems Randall became interested in who won. See more on the comics page.
**Was there until [[1561: Water Phase Diagram]] was up on [https://web.archive.org/web/20150807181044/http://xkcd.com/ 2015-08-07]. Then it returned back to the previous header with only the promotion of the book.

===2015-05-15 - Thing Explainer details===
*[http://web.archive.org/web/20150515060322/http://www.xkcd.com/ 2015-05-15]
**[[1525: Emojic 8 Ball]]
**This was a more detailed promotion for Randall's new book: [[Thing Explainer]] to be published in November 2015, more than half a year after the announcement, compared to the previous change which was just a line and a link.
**The text:
***A picture of the open book is shown with diagrams of a human cell on the left page and suspension bridges on the right. All held in blue nuances. And arrow goes from the first word of the text to the right to the book on the left. The text is also blue except the title of the book which is in red:
****New book: Thing Explainer
****Up Goer Five-style diagrams of things (explained in the then hundred most common words)
***Below this image is a line of text with the first word in black and the other are four links to where to preorder the book:
****Preorder: [https://www.amazon.com/Thing-Explainer-Complicated-Stuff-Simple/dp/0544668251 Amazon], [https://www.barnesandnoble.com/w/thing-explainer-randall-munroe/1121864432?ean=9780544668256#/ Barnes & Noble], [https://www.indiebound.org/book/9780544668256 Indie Bound], [https://www.hudsonbooksellers.com/thingexplainer Hudson]
***The image above the preorder line is a link to the [[Blag]] post [https://blog.xkcd.com/2015/05/13/new-book-thing-explainer/ New book: Thing Explainer].
**Changed while [[1534: Beer]] was up on [https://web.archive.org/web/20150605082643/http://xkcd.com/ 2015-06-05], but only to add other information. The main promotion of the book stayed the same.

===2015-05-14 - New book Thing Explainer===
*[https://web.archive.org/web/20150514053623/http://www.xkcd.com/ 2015-05-14]
**[[1524: Dimensions]] was up.
***A single line announced the new [[Thing Explainer]] book, with link to the [[Blag]] post from the day before.
**The text:
***New book: [https://blog.xkcd.com/2015/05/13/new-book-thing-explainer/ Thing Explainer!]
*The [[:Category:Book promotion|promotion of the book]] stayed up with some changes for [[xkcd_Header_text#2015-12-13_-_Thing_Explainer_is_available|more than 10 month]] first stopping when Randall had [[xkcd_Header_text#2016-04-01_-_The_xkcd_April_1st_comic_is_currently_experiencing_technical_difficulties|problems with his April Fool's comic]] in 2016... It is a record length.
**The first came already the day after so this short announcement was only up on this day and ended with the next comic. See above.
**See more details on the promotion of the book on the Thing Explainer page [[Thing_Explainer#Promotion_at_the_xkcd_home_page|here]].

===2015-02-11 - Back to standard text===
*[https://web.archive.org/web/20150211154103/http://xkcd.com/ 2015-02-11]
**When [[1485: Friendship]] came out the text returned to the standard xkcd header:
***xkcd updates every Monday, Wednesday, and Friday.
**It stayed like this until [[1523: Microdrones]] was up on [https://web.archive.org/web/20150512184622/http://xkcd.com/ 2015-05-12], so just a day more than three months.

===2015-02-04 - Valentine cards only===
*[https://web.archive.org/web/20150204051152/http://xkcd.com/ 2015-02-04]
**[[1482: NowPlaying]] came out as it changed.
***After the last day of ordering t-shirt had passed it changed back to the picture with the Valentine cards from the previous header, but without the t-shirt picture.
***See that [[#2015-01-29 - Valentine cards and shirt|header change]], but only the first picture described.
**Ended while [[1484: Apollo Speeches]] was up on [https://web.archive.org/web/20150210005540/http://xkcd.com/ 2015-02-10].

===2015-02-02 - Last day shirt===
*[https://web.archive.org/web/20150202092804/http://xkcd.com/ 2015-02-02]
**[[1481: API]] came out as it changed.
***Just letting people know it is the last chance to order the binary t-shirt.
***There was just a line of text:
**The text was:
***Today is the last day to order the limited-run [https://web.archive.org/web/20150202092804/http://teespring.com/xkcdbinaryheart binary heart shirt]!
***The last words is link to the shirt in the shop.
**Ended before the next comic was up, but still the day after, when it was too late to order: [https://web.archive.org/web/20150203022036/http://xkcd.com/ 2015-02-03].

===2015-01-29 - Valentine cards and shirt===
*[http://web.archive.org/web/20150129183442/http://xkcd.com/ 2015-01-29]
**[[1479: Troubleshooting]] was up when it changed.
***It was to tell about both the two previous updates in the same header- Both about the collaboration to make science themed Valentine's Day cards and his new Valentine t-shirt.
***There where two pictures, with a promotion of the two products and a link to them in the shop.
***On the left was text about the cards with a small drawing to the right of the text showing the four cards.
****An ant talking to an aphids; Earth rotating about the sun but locked so one side melts; an ant with a fungus growing from it's head with a heart, and a Velociraptor skeleton where the last bit of the tail is put on by a person. The text on the cards are unreadable, but they can be seen via the link.
***The text (in three lines) was:
****Webcomic science Valentine card collaboration
****The [https://web.archive.org/web/20150127161237/http://store.xkcd.com/products/webcomic-science-valentines link to the cards] from the picture.
***The picture on the left shows binary numbers 0 and 1 in white on a black background. The middle of the three lines of those have message in red text.
***The text:
****0 1 0 1 0 Binary heart 1 1 1
****1 1 1 Valentine shirt 0 1
****0 0 0 1 [limited run] 0 0 1
****The [http://web.archive.org/web/20150125080756/http://teespring.com/xkcdbinaryheart link to the shirt] from the picture.
**Ended while [[1480: Super Bowl]] was up on [https://web.archive.org/web/20150201015913/http://xkcd.com/ 2015-02-01].

===2015-01-27 - Valentine's Day cards===
*[http://web.archive.org/web/20150127161237/http://xkcd.com/ 2015-01-27]
**[[1478: P-Values]] was up when it changed.
***It was to tell that about a collaboration to make science themed Valentine's Day cards.
***There was just two lines of text:
**The text was:
***I've teamed up with three other webcomic artists
***to make [https://web.archive.org/web/20150127161237/http://store.xkcd.com/products/webcomic-science-valentines a set of science-themed Valentine's Day cards]!
**There was a link to the cards on the store.
**Ended while [[1479: Troubleshooting]] was up [https://web.archive.org/web/20150128172147/http://xkcd.com/ 2015-01-28].

===2015-01-24 - Get shirts in store===
*[http://web.archive.org/web/20150124110707/http://xkcd.com/ 2015-01-24]
**[[1477: Star Wars]] came out as it changed.
***It was to tell about a new type of t-shirt for Valentine Day.
***There was just two lines of text:
**The text was:
***For Valentine's Day, you can get a binary heart shirt
***(from {{xkcd|99|comic #99!}}) in [http://web.archive.org/web/20150125080756/http://teespring.com/xkcdbinaryheart a limited run on TeeSpring]
**There was a link to [[99: Binary Heart]] and to the relevant t-shirt on the [https://teespring.com/ Teespring] home page.
**Ended while [[1478: P-Values]] was up [http://web.archive.org/web/20150126133139/http://xkcd.com/ 2015-01-26].

===2014-12-22 - Get shirts in store===
*[http://web.archive.org/web/20141222233233/http://xkcd.com/ 2014-12-22]
**[[1463: Altitude]] came out as it changed.
***After the Christmas sale deadline there was still merchandise in the [https://store.xkcd.com/ xkcd store].
***There was just a line of text:
**The text was:
***You can get xkcd shirts, prints, and posters in the [http://shop.xkcd.com/ store]!
**The word store was a link to the shop.
**Ended while [[1476: Ceres]] was up [http://web.archive.org/web/20150123102318/http://xkcd.com/ 2015-01-23].

===2014-12-19 - Back to previous header===
*[http://web.archive.org/web/20141219092349/http://www.xkcd.com/ 2014-12-19]:
**[[1462: Blind Trials]] came out as it changed.
*It changed back to the exact same heading as before the one with order now here below.
**See [[#2014-12-17 - Christmas deadline|2014-12-17]] below for all details.
**Ended while [[1462: Blind Trials]] was still up [http://web.archive.org/web/20141221172450/http://www.xkcd.com/ 2014-12-21].

===2014-12-18 - Order now===
*[http://web.archive.org/web/20141218090650/http://www.xkcd.com/ 2014-12-18]
**[[1461: Payloads]] was still up when it changed.
***It was to alert that the deadline for shipping before Christmas from the [https://store.xkcd.com/ xkcd store] was Friday and that it was rapidly approaching. This was a follow up on the [[#2014-12-17 - Christmas deadline|Wednesdays announcement]] the day before.
***The image was just four lines of text with several red and blue words.
**The text was:
***The xkcd store Christmas shipping deadline is Friday!
***Once it passes, there is no going back. The arrow of time drags us all
***Inexorably forward toward decay and disorder. toward the end of all things.
***Towards the empty silence of the grave. Order now!
**The entire drawing was a link to the [https://store.xkcd.com/ xkcd store], not just the blue text.
**Ended a day later while [[1461: Payloads]] was still up [http://web.archive.org/web/20141216084107/http://xkcd.com/ 2014-12-16].

===2014-12-17 - Christmas deadline===
*[http://web.archive.org/web/20141217085320/http://www.xkcd.com/ 2014-12-17]
**[[1461: Payloads]] came out as it changed.
***It was to alert that the deadline for shipping before Christmas from the [https://store.xkcd.com/ xkcd store] was Friday. This was announced Wednesday two days before the deadline.
***The image was just text with the last word in each line in red and the xkcd store blue as a link.
**The text was:
***Looking for a gift?
***xkcd store Christmas shipping deadline is Friday!
**The entire drawing was a link to the [https://store.xkcd.com/ xkcd store], not just the blue text
**Ended a day later while [[1461: Payloads]] was still up!

===2014-12-03 - Christmas shopping===
*[http://web.archive.org/web/20141203132024/http://www.xkcd.com/ 2014-12-03]
**[[1455: Trolley Problem]] came out as it changed.
***It was to announce the start of the Christmas shopping on the [https://store.xkcd.com/ xkcd store]
***Four boxes with shipping details are shown. Two green and two red, alternating from green. Between them are three text messages in two, two and three lines.
**The text was:
***xkcd store
***Christmas shopping
***I will probably not ship you a bobcat.
**The entire drawing was a link to the [https://store.xkcd.com/ xkcd store].
**The bobcat is a reference to [[325: A-Minus-Minus]].
**Ended while [[1460: SMFW]] was up [http://web.archive.org/web/20141216084107/http://xkcd.com/ 2014-12-16].

===2014-11-29 - Thanks - Emily===
*[http://web.archive.org/web/20141129211604/http://xkcd.com/ 2014-11-29]
**[[1453: fMRI]] was still up when it changed.
***It was to thanks for all the help his friend Emily with cancer got through among other his previous header text [[#2014-11-27 - Help Emily| Help Emily]].
***That only needed to be up two days before the goal was met.
**The text was:
***Thank you for helping my friend Emily.
***It means so much.
**Ended three days later while [[1454: Done]] was up [http://web.archive.org/web/20141202065133/http://xkcd.com/ 2014-12-02].

===2014-11-27 - Help Emily===
*[http://web.archive.org/web/20141127005239/http://xkcd.com/ 2014-11-27]
**[[1452: Jurassic World]] came out as it changed.
***It was to help a friend who got cancer by raising money for her.
**The text was:
***Hey all. My friend Emily—the economist who helped
***me with my {{xkcd|980|money chart}}—has been fighting cancer. She's
***having a rough time and could use some [http://web.archive.org/web/20141128183414/http://www.gofundme.com/e07dqk help]. Thank you.
**There are two links, one to the [[980: Money]] comic she helped Randall create, and one for her Go Fund Me page to raise money for her cancer cure.
***The help link above is to the archived version from that time, but the link was still active in August 2019: [https://www.gofundme.com/e07dqk Helping Emily Fight Cancer].
**Ended while [[1453: fMRI]] was up [http://web.archive.org/web/20141128070838/http://www.xkcd.com/ 2014-11-28].
***She did thus not get a permanent header as did Becky on the [[#Seven_Years|Seven Years]] comic.

===2014-10-02 - what if? bestseller===
*[http://web.archive.org/web/20141002211139/http://xkcd.com/ 2014-10-02]
**[[1428: Move Fast and Break Things]] was up when it changed from the [[#2014-09-02 - what if? book out|book is out]].
**This was a month after the ''[[What If? (book)|What If?]]'' book came out.
***It added a line of red text beneath the previous header to announce that the book was the #1 New York bestseller.
**The text was:
***My book is out!
***(#1 New York bestseller!)
**The entire image was a link to the [https://whatif.xkcd.com/book/ The Book] page on the [https://whatif.xkcd.com/ what if?] page on xkcd. post.
**Ended while [[1451: Background Screens]] was up [http://web.archive.org/web/20141125234520/http://xkcd.com/ 2014-11-25].

===2014-09-04 - what if? book out===
*[http://web.archive.org/web/20140904150600/http://xkcd.com/ 2014-09-04]
**[[1416: Pixels]] was up when it changed from the [[#2014-09-02 - what if? book out today|book is out today]].
**This was two days after the ''[[What If? (book)|What If?]]'' book came out.
***It only removed to today from the previous header, that had only been up two days.
**The text was:
***My book is out!
**The entire image was a link to the [https://whatif.xkcd.com/book/ The Book] page on the [https://whatif.xkcd.com/ what if?] page on xkcd. post.
**Ended while [[1428: Move Fast and Break Things]] was up [http://web.archive.org/web/20141001130827/http://xkcd.com/ 2014-09-01].

===2014-09-02 - what if? book out today===
*[http://web.archive.org/web/20140902125802/http://xkcd.com/ 2014-09-02]
**[[1415: Ballooning]] was up when it changed from the [[#2014-07-23 - what if? book tour|book tour header]].
**This was the day the ''[[What If? (book)|What If?]]'' book came out. [[Cueball]] standing to the left of the text with arms raised shouts this out.. The word Book is underlined and blue to indicate a link.
**The text was:
***My book is out today!
**The entire image was a link to the [https://whatif.xkcd.com/book/ The Book] page on the [https://whatif.xkcd.com/ what if?] page on xkcd. post.
**Ended while [[1416: Pixels]] was still [http://web.archive.org/web/20140903134518/http://xkcd.com/ 2014-09-03].

===2014-07-23 - what if? book tour===
*[http://web.archive.org/web/20140723180600/http://xkcd.com/ 2014-07-23]
**[[1398: Snake Facts]]
**This was a promotion of his book tour for the ''[[What If? (book)|What If?]]'' book made by [[Cueball]] standing to the left of the text with arms raised. Several parts of the text was underlined and blue to indicate links.
**The text was:
***I'm going on a book tour! click here for a list of stops.
***Or click anywhere-this whole image is one link because I've never gotten the hang of HTML imagemaps.
**The entire image was a link to the [[Blag]] post: [https://blog.xkcd.com/2014/07/22/what-if-book-tour/ What If book tour!].
***Later Randall commented on this lacking ability in the comic: [[1572: xkcd Survey]].
***He also mentions it in one of the [[#xkcd_Header_text#2019-07-09_-_Drawings_from_How_To|promotions]] for his [[How To]] book.
***He much later he again mentions that html is hard, thus explaining why the entire image is a link instead of the actual blue highlighted link in one of the promotions for [[xkcd_Header_text#2022-08-11_-_Preorder_What_if.3F_2_-_with_image|what if? 2]].
**Ended while [[1415: Ballooning]] was still up [http://web.archive.org/web/20140901113916/http://xkcd.com/ 2014-09-01].

===2014-03-13 - what if? announced===
*[http://web.archive.org/web/20140313070951/http://xkcd.com/ 2014-03-13]
**[[1341: Types of Editors]] was up.
**This was the first promotion of Randall's new ''[[What If? (book)|What If?]]'' book which is shown next to two lines of text.
**The text was:
***News:
***I'm publishing a ''what if'' book!
**The entire image was a link to the [[Blag]] post: [https://blog.xkcd.com/2014/03/12/what-if-i-wrote-a-book/ What if I wrote a book?]
**Ended while [[1397: Luke]] was up [http://web.archive.org/web/20140722142115/http://xkcd.com/ 2014-07-22].

===2014-01-09 - Back to standard text===
*[https://web.archive.org/web/20140109190927/http://www.xkcd.com/ 2014-01-09]
**When [[1314: Photos]] was still up when the text returned to the standard xkcd header:
***xkcd updates every Monday, Wednesday, and Friday.
**It stayed until [https://web.archive.org/web/20140312070248/http://xkcd.com/ 2014-03-12] when [[1340: Unique Date]] was up, a bit more than two months.

===2013-12-21 - Deadline for Christmas shipping has passed===
*[https://web.archive.org/web/20131221043417/http://www.xkcd.com/ 2013-12-21]
**It changed when [[1306: Sigil Cycle]] came out.
**This came up when it was too close to Christmas in 2013 for shipping to arrive in time for Christmas. And Randall makes a note of this, but lets people know that they could still buy presents...
**The text was
***The deadline for guaranteed Christmas shipping has passed, but if you order something from the [http://store.xkcd.com/ xkcd store], we'll get it to you as fast as possible!
**Ended when [[1314: Photos]] was up on [https://web.archive.org/web/20140108181520/http://www.xkcd.com/ 2014-01-08].

===2013-12-06 - Empty header===
*[https://web.archive.org/web/20131206213503/http://xkcd.com/ 2013-12-06]
**It changed when [[1300: Galilean Moons]] came out.
***There just where no header text. This has not happened since. It looks really weird.
**Ended when [[1305: Undocumented Feature]] was up on [https://web.archive.org/web/20131220005306/http://xkcd.com/ 2013-12-20].

===Changes not documented yet 3===
*More changes will for sure be here between this and the one below.

====Interesting links in the Archive 3====
*Just put the link here with a date and maybe a short note:
*[https://web.archive.org/web/20131205202730/http://xkcd.com/ 2013-12-05]: Xmas sale before above
*[https://web.archive.org/web/20130315162227/http://xkcd.com:80/ 2013-03-15]: Empty follows below

===2013-03-15 - Empty header===
*[https://web.archive.org/web/20130315162227/http://xkcd.com:80/ 2013-03-15]
**It changed while [[1186: Bumblebees]] was on the front page.
***After the text saying a comic would be delayed disappeared no text replaced this.
***So the header was left empty!
**This lasted until [https://web.archive.org/web/20130318072820/http://xkcd.com/ 2013-03-18] while [[1187: Aspect Ratio]] was up.

===2013-03-13 - Comic will be delayed===
*[https://web.archive.org/web/20130313133631/http://xkcd.com/ 2013-03-13]
**It changed when [[1184: Circumference Formula]] came out, likely because the next comic was delayed.
***But there is a gap of three days before where no archived version exist, so cannot say if there where more than a few hours with this text.
**The text:
***The comic will be delayed until late morning EDT.
**Ended when [[1185: Ineffective Sorts]] was up on [https://web.archive.org/web/20130313175306/http://xkcd.com:80/ 2013-03-13].
***That was later same day as the first archived version. But could have been longer as mentioned above.

===2012-11-26 - xkcd store===
*[https://web.archive.org/web/20121126235628/http://xkcd.com/1138/ 2012-11-26]
**It changed while [[1138: Heatmap]] was up.
***Notice that the above link is not from the main page, but from {{xkcd|1138}}.
***There was a gap of five days in the archive of the main page.
***The first day that it was archived from the front page was on [https://web.archive.org/web/20121201111432/http://xkcd.com/ 2012-12-01], while [[1141: Two Years]] was up.
**The standard header text is replaced with an image that makes it seem like a rip is being torn in the white region where the text used to be. Beneath the white material that has now been ripped, some text can partly be seen. It is possible to read it.
**The text:
***xkcd store
****The image is a link to the [http://store.xkcd.com/ xkcd store] (tadaaa!)
**Ended when [[1183: Rose Petals]] was up on [https://web.archive.org/web/20130311073948/http://xkcd.com:80/1183/ 2013-03-11]
***The above link is from {{xkcd|1183}}.
***Last time the front page was archived with it was though on [https://web.archive.org/web/20130309010403/http://xkcd.com/ 2013-03-09].

===2012-10-24 - Back to standard text===
*[https://web.archive.org/web/20121024082017/http://xkcd.com:80/ 2012-10-24]
**While [[1124: Law of Drama]] was on the front the header returned to the standard xkcd header:
***xkcd updates every Monday, Wednesday, and Friday.
**It stayed until [https://web.archive.org/web/20121126035129/http://xkcd.com:80/ 2012-11-26] when [[1138: Heatmap]] was up, a few days more than a month.

===2012-10-17 - New What-If - Lightning===
*[https://web.archive.org/web/20121017232102/http://xkcd.com/1121/ 2012-10-17]
**Probably while [[1122: Electoral Precedent]] was up.
***But the link above showing it was up on the 2012-10-17 is from the previous comics page {{xkcd|1121}} [[1121: Identity]].
***But the first version archived with this header is saved on [https://web.archive.org/web/20121018082304/http://xkcd.com/ 2012-10-18]
**Randall promotes another New What-If article.
***See the ''[[what if? (blog)|what if?]]'' article ''{{what if|16|Today's topic: Lightning}}''.
**The text
***New What-If article:
***[http://what-if.xkcd.com/16/ What if lightning struck while you were ...]
**This lasted until [https://web.archive.org/web/20121023023404/http://xkcd.com/1121/ 2012-10-23] when [[1124: Law of Drama]] was on the front page
***This link is though from {{xkcd|1121}}.
***The last this version was archived on the front page was the day before on [https://web.archive.org/web/20121022120008/http://xkcd.com:80/ 2012-10-22].

===2012-10-10 - New What-If - Mariana Trench Explosion===
*[https://web.archive.org/web/20121010003837/http://xkcd.com/ 2012-10-10]
**[[1118: Microsoft]] was still up at this time.
**Randall promotes another New What-If article.
***See the ''[[what if? (blog)|what if?]]'' article ''{{what if|15|Mariana Trench Explosion}}''.
**The text
***New What-If article:
***[http://what-if.xkcd.com/15/ What if you set off a nuclear bomb in the Mariana Trench?].
**This lasted until [https://web.archive.org/web/20121016055538/http://xkcd.com:80/ 2012-10-16] when [[1121: Identity]] was up.

===2012-10-02 - This week's What-If - Short Answer Section===
*[https://web.archive.org/web/20121002231724/http://www.xkcd.com/ 2012-10-02]
**[[1115: Sky]] was still up at this time.
**Randall promotes another New What-If article.
***See the ''[[what if? (blog)|what if?]]'' article ''{{what if|14|Short Answer Section}}''.
**The text
***In this week's What-If article I [https://what-if.xkcd.com/14/ answer multiple reader questions].
**This lasted until [https://web.archive.org/web/20121008112434/http://xkcd.com/ 2012-10-08] when [[1118: Microsoft]] was up.

===2012-09-26 - New What-If - Laser Pointer===
*[https://web.archive.org/web/20120926163111/http://xkcd.com/1108/ 2012-09-26]
**[[1113: Killed in Action]] was up at this time.
***The link above showing it happened on the 26th is from {{xkcd|1108}}
***The first day this version was archived on the front page was on [https://web.archive.org/web/20120928003838/http://xkcd.com:80/ 2012-09-28]
**Randall promotes another New What-If article.
***See the ''[[what if? (blog)|what if?]]'' article ''{{what if|13|Laser Pointer}}''.
**The text
***New What-If article:
***[http://what-if.xkcd.com/13/ If everyone aimed a laser pointer at the Moon at once, would it change color?]
**This lasted until [https://web.archive.org/web/20121001080517/http://xkcd.com/ 2012-10-01] when [[1115: Sky]] was up.

===2012-09-18 - what-if.xkcd.com - Raindrop===
*[https://web.archive.org/web/20120918143653/http://www.xkcd.com/1108/ 2012-09-18]
**[[1109: Refrigerator]] was still up at this time.
***The link above showing it happened on the 18th is from {{xkcd|1108}}
***The first day this version was archived on the front page was on [https://web.archive.org/web/20120919015232/http://xkcd.com/ 2012-09-19]
**Randall promotes another What-If article on the what-if page.
***See the the ''[[what if? (blog)|what if?]]'' article ''{{what if|12|Raindrop}}''.
**The text
***what-if.xkcd.com: [https://what-if.xkcd.com/12/ What if all of a storm's water fell in a single raindrop?].
**This lasted until [https://web.archive.org/web/20120925090123/http://xkcd.com:80/ 2012-09-25] when [[1112: Think Logically]] was up.

===Changes not documented yet 2===
*The above is the last documented.
**There will for sure be more changes earlier than this.

====Interesting links in the Archive 2====
*Just put the link here with a date and maybe a short note:
*[https://web.archive.org/web/20120917052827/http://xkcd.com:80/ 2012-09-17]: What if Droppings ends.
*[https://web.archive.org/web/20120718231719/http://www.xkcd.com/ 2012-07-18] Next stores header text

===2012-07-10 - New: what-if.xkcd.com===
*[https://web.archive.org/web/20120710114846/http://xkcd.com/1078/ 2012-07-10]
**This was a special change happening over a few days. The above "new" header text from the given date is actually shown on the previous comic [[1078: Knights]].
***Another example from [https://web.archive.org/web/20120710072249/http://xkcd.com:80/1070 2012-07-10] is shown for [[1070: Words for Small Sets]].
**The comic on the main page released on [https://web.archive.org/web/20120709045709/http://xkcd.com:80/ 2012-07-09] was [[1079: United Shapes]], but that comic had a [[xkcd_Header_text#United_Shapes|unique header text]] upon its release.
***So both on the 9th as shown above and on [https://web.archive.org/web/20120710114846/http://xkcd.com/1078/ 2012-07-10] the header text was different on the front than on all other pages.
****As can be read in the link above, the new header text actually got incorporated into the unique text, so that after the next comic was released on [https://web.archive.org/web/20120711234408/http://xkcd.com/1079/ 2012-07-11] the current new header text and a smaller version of the original unique header text was now shown on the Unites Shapes page.
****{{xkcd|1079|And it was never changed back}}.
**The first version of the new text from the 10th was only active one day:
***The text:
****New site: what-if.xkcd.com, where I abuse science to answer hypothetical questions. I'll answer a new question every Tuesday.
*****The link was not an active link. And this was never shown on the front page, but on all other comics.
**Already on [https://web.archive.org/web/20120711223349/http://xkcd.com/1078/ 2012-07-11] when [[1080: Visual Field]] was released the new header changed a bit
***At this time it most have been shown on the front page, but the link above is again from [[1078: Knights]].
****For some reason the front page was not saved on either the 11th or 12th, so no version of the front page with Visual Field exist
****The first archived version of the front page with this new header text was from [https://web.archive.org/web/20120713154207/http://xkcd.com/ 2012-07-13] when [[1081: Argument Victory]] was on the front page.
**The final text:
***New: [http://what-if.xkcd.com/1/ what-if.xkcd.com]: abusing science to answer hypothetical questions.
***I'll answer a new reader question every Tuesday.
****This time the link was active and directs to the new ''[[what if? (blog)|what if?]]'' blog and its first entry {{what if|1|Relativistic Baseball}}
**The whole idea was that Randall released the new what if? blog on the 10th of July 2012. And thus would like to make a promotion of it.
***And then he timed it so poorly that the front page had a different header than the rest of the comics.
***It was so annoying for him that he actually changed the header for Unites Shapes manually so that page also showed the new link. Maybe even before it left the front page, but that has not been documented in the archive.
***And then he forgot about it when the header changed for all the other comics, so it is now a relic of the promotion of his first what if release.
**The what if promotion continued for a long time, but the final version from above only lasted until 17th at the latest. There is again no archived versions of the front page from the 15th, 16th or 17th.
***The last time it was archived on the front page was [https://web.archive.org/web/20120714062857/http://xkcd.com/ 2012-07-14], when [[1081: Argument Victory]] was still up.
***But on [https://web.archive.org/web/20120715070938/http://xkcd.com:80/1081/ 2012-07-15] it was still shown on the page for Argument Victory and same for [https://web.archive.org/web/20120716235458/https://www.xkcd.com/998/ 2012-07-16] on [[998: 2012]]
****So seemed it stayed up while [[1082: Geology]] was up on the 16-17/7.

===2012-04-09 - Standard text plus store link===
*[https://web.archive.org/web/20120409190952/http://xkcd.com/1026/ 2012-04-09]
**It changed when [[1040: Lakes and Oceans]] came up.
***The above link to prove this is though from comic {{xkcd|1026}} [[1026: Compare and Contrast]] the first to be found that where archived on the 9th.
***The first archived version on the main page is from [https://web.archive.org/web/20120411053543/https://xkcd.com/ 2012-04-11] when [[1041: Whites of Their Eyes]] was up.
***There where no archived version of the front page on the 9th or 10th while Lake and Oceans was up. So it was also first on the 11th that this new text could be seen, but only when it had moved to its own page number [https://web.archive.org/web/20120411052948/http://xkcd.com/1040/ 1040].
****The change probably came because of this special comic, which may became a [https://store.xkcd.com/collections/posters/products/lakes-oceans-poster poster].
**The update was to add a promotion for the store under the standard header text.
**The text
***XKCD updates every Monday, Wednesday, and Friday.
***You can get prints, posters, and t-shirts in the [http://store.xkcd.com/ store].
**This lasted until [https://web.archive.org/web/20120709004956/http://www.xkcd.com/ 2012-07-09] when [[1078: Knights]] was up, exactly three months, so although not only the standard text, the standard text was first for three months and three days, see [[#2012-04-05 - Back to standard text|below]].

===2012-04-05 - Back to standard text===
*[https://web.archive.org/web/20120405195956/http://www.xkcd.com/1021/ 2012-04-05]
**While [[1038: Fountain]] was on the front the header returned to the standard xkcd header:
***xkcd updates every Monday, Wednesday, and Friday.
**The link above to prove the date is seen on [[1021: Business Plan]].
***The first archived version on front page is from [https://web.archive.org/web/20120406111048/http://xkcd.com/ 2012-04-06], when [[1039: RuBisCO]] was up.
***A version showing Fountain with this can be found on it's own page {{xkcd|1038}} on [https://web.archive.org/web/20120406085618/http://xkcd.com:80/1038/ 2012-04-06].
****When it was archived while on the front page it still had the previous header on [https://web.archive.org/web/20120404210927/http://xkcd.com:80/ 2012-04-05].
**It stayed up, unchanged, until [https://web.archive.org/web/20120408200414/http://xkcd.com:80/ 2012-04-08] when [[1039: RuBisCO]] was up. So only three days.
***But [[#2012-04-09- Standard text plus store link|the change]] did not remove the standard text but just added a link to the store. And this version, still with the standard text at the top stayed for three more months.

===2012-03-28 - Visiting Newport News===
*[https://web.archive.org/web/20120328103319/http://xkcd.com/ 2012-03-28]
**[[1035: Cadbury Eggs]] was on the front when it changed.
***From the end of March 2012, there is a problem with the archived versions of xkcd, so they do not load properly and do not include the comic picture.
**It was to announce a talk Randall gave at his old school.
**The text:
***I'm [https://blog.xkcd.com/2012/03/22/im-visiting-cnu-on-april-4th/ visiting] Newport News, VA next week, where I'll be speaking at CNU, my old school. If you want to come, reserve a seat [https://web.archive.org/web/20120329214411/http://www.cnu.edu/pcs/xkcd/index.asp here]!
****The first link it to a post in the [[Blag]]: [https://blog.xkcd.com/2012/03/22/im-visiting-cnu-on-april-4th/ I’m visiting CNU on April 4th].
****The other link is no longer working, but the link above goes to an archived version.
**There was a special situation with this header text. For three days it was not on the front page, as the [[:Category:April fools' comics|April fools' comic]] [[1037: Umwelt]] came out and stayed from April 1st to April 3rd on the front page.
***This comic had it's own [[#Unique header text|unique header text]] from the start, one that has [[#Umwelt|stayed like this]] since!
****So from [https://web.archive.org/web/20120401151639/http://xkcd.com:80/ 2012-04-01] to [https://web.archive.org/web/20120403223453/http://www.xkcd.com/ 2012-04-03] the front page had another header:
*****You can get posters, prints, and t-shirts in the [https://store.xkcd.com/ xkcd store].
***But all the other comics kept the Visiting header on all three days as shown here:
****[https://web.archive.org/web/20120401214214/http://xkcd.com:80/1036/ 2012-04-01] from[[1036: Reviews]].
****[https://web.archive.org/web/20120402150258/http://xkcd.com/1019 2012-04-02] from [[1019: First Post]].
****[https://web.archive.org/web/20120403164523/http://xkcd.com:80/1036/ 2012-04-03] from [[1036: Reviews]].
*****The one from the 2nd of April was hardest to find, but the most important, because that was clearly in the time period where Umwelt was up, thus definitely proving that the other pages had a different header than the front page. This is rare.
**It returned to the front page on [https://web.archive.org/web/20120404210927/http://xkcd.com:80/ 2012-04-04] and stayed up until [https://web.archive.org/web/20120405195956/http://www.xkcd.com/1021/ 2012-04-05] when [[1038: Fountain]] was up.
***The link from the 5th though is from {{xkcd|1021}} [[1021: Business Plan]], the only comic archived on the 5ht to be found.
****The previous link was the last time it was archived while on the front page.

===2012-03-12 - xkcd Holistic Browser===
*[https://web.archive.org/web/20120312185125/http://xkcd.com/ 2012-03-12]
**[[1028: Communication]] was up at the time.
***From here the archive doesn't load the page properly so it is really boring to document. This goes for both first and last day of this text.
**The text:
***New: [https://web.archive.org/web/20120318153220/http://holistic.xkcd.com/ holistic.xkcd.com], the least useful web navigation tool ever.
****The link is now dead, but the link above is to an archived version.
****On that page there is the following text:
*****The XKCD Holistic Browser
*****Because we are all one.
*****Type a web address
*****and you'll be taken to one
*****typed by someone else.
*****URL:
*****Warning: This allows strangers to direct your browser!
*****They may send you to pages containing
*****porn, viruses, or Justin Bieber fanfiction.
*****At the very least, turn on private browsing.
**During the time this header was active the comic [[1031: s/keyboard/leopard/]] came out.
***It had its own [[xkcd_Header_text#Unique_header_text|unique header text]] which thus replaced this text on the front page for two days.
***But it did not replace it on all the other pages so this was the active header text during the entire period, see more here: [[xkcd_Header_text#s.2Fkeyboard.2Fleopard.2F|s/keyboard/leopard/]]
**This lasted till [https://web.archive.org/web/20120327050311/http://xkcd.com/1033 2012-03-27] while [[1034: Share Buttons]] was up.
**But the last archived version with this on the front page was the day before [https://web.archive.org/web/20120326180811/http://xkcd.com// 2012-03-26].
***The link from 27th is from an archived version of [[1033: Formal Logic]].
*[https://web.archive.org/web/20120311135259/http://xkcd.com/ 2012-03-11] Text before. For net entry below...

[[Category:Design of xkcd.com]]
{{xkcdmeta}}

2821: Path Minimization

2023-08-31T11:31:27Z

Capybarafan436: /* Transcript */ Whoops, forgot Ponytail.

{{comic
| number = 2821
| date = August 28, 2023
| title = Path Minimization
| image = path_minimization_2x.png
| imagesize = 562x559px
| noexpand = true
| titletext = Of course you get an ice cream cone for the swimmer too! You're not a monster.
}}

==Explanation==
{{incomplete|Created by WAITING AN HOUR BEFORE SWIMMING - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

In this comic, it appears that Cueball, standing on shore, is observing a swimmer who is possibly (but not obviously) in distress. The comic illustrates five potential paths that can be taken to reach the swimmer, each with a different reason to make them viable, in the manner of demonstrating different optimal strategies that can be chosen.

The first path is a direct line from Cueball, straight to the swimmer, which allows for the minimum possible distance to be traveled, some on land and the remainder in the water.

The second path travels more obliquely from Cueball to the water and then at a sharper angle to the swimmer. This path would take the shortest amount of time, presuming that Cueball would move faster on land (covering more of the distance) and slower through the water (but less distance). The exact angles would depend on how much faster Cueball is on land than in the water. The relationship between speeds and angles is the same as that in {{w|Snell's law}} for light passing between two media.

The third path travels at a far more oblique angle to the water, such that the subsequent swimming path is entirely perpendicular to the shoreline, adding to the amount of time spent on land in order to minimize the time spent swimming. Depending on one's swimming ability versus running ability, this could be the safest path to take. It might also be more sensible to keep the target in clear sight for as long as possible, from the land, then aim exactly away from shore when both your head and theirs are barely at wave-height (though currents may complicate this). But this is a completely different reason from the distance or time preferences.

The fourth path travels nearly parallel to the beach. In fact moving slightly ''away'' from the swimmer but towards an intermediate goal: an ice cream stand. After that, the path turns and aims straight towards the swimmer, as all the others eventually do (although it is not made clear at this point if Cueball will spend time eating his ice cream on the beach, or will attempt to carry and possibly eat an ice cream whilst swimming).

The fifth and final path, barely recognizable as a path, points off the top of the comic and reappears at the bottom. This path presumably travels around the entire world, likely stopping for many, ''many'' rest breaks. It is labeled as the path that ''maximizes'' time. It should be noted that, by the definition given, it is theoretically possible to stretch the maximum time taken out forever by simply walking away and never returning.

You could also fulfill the criteria of reaching the target in finite, but arbitrarily long, time by following a {{w|random walk}}(+swim) or even follow a {{w|space-filling curve}} carefully chosen to be the maximally finite scenario. Or you could simply choose any path, and stop for an arbitrarily long time, or travel at a speed approaching zero. In the comic, however, a requirement for simplicity of path may dictate the use of something close to the opposing {{w|great-circle distance}}, or a variation that has a maximal swim-time even without ''undue'' time-wasting detours, and assume equal speeds of travel on all routes.

The comic pokes fun at two famous physical/mathematical problems that are usually stated as happening on a beach. The first is the Lifeguard problem, which Richard Feynman, in his book ''QED'', uses to illustrate {{w|Fermat's principle}}, or principle of least time, which states that the path taken by a light ray between two given points is the path that can be traveled in the least time. This is closely related to {{w|Stationary-action principle}} for mechanical systems. In Feynman's words:

''"Finding the path of least time for light is like finding the path of least time for a lifeguard running and then swimming to rescue a drowning victim: the path of least distance has too much water in it; the path of least water has too much sand in it; the path of least time is a compromise between the two."'' - ''Richard Feynman, QED - The Strange Theory of Light and Matter (1988, Princeton University Press), Chapter 2.''

The second problem referenced in this comic is the [https://gametheory101.com/courses/game-theory-101/hotellings-game-and-the-median-voter-theorem Beach Vendor Problem], which is stated as follows. Suppose that on a long beach there are two ice cream vendors. Customers are uniformly distributed on the beach and each person will go get the ice cream at the closest vendor. Each vendor wants to maximize the number of customers that buy at their place. To minimize the customer's walking time, the optimal configuration would be to have one vendor at 1/4 of the beach length and the other at 3/4, but {{w|Hotelling's law}} predicts that the two shops will converge to the middle of the beach, in an attempt to steal as many customers as possible from the competition. This is a case of {{w|Nash equilibrium}} that is also related to the {{w|Median voter theorem}}. If the number of vendors is larger than 2, the problem may become [https://gametheory101.com/tag/hotellings-game/ considerably more complicated].

The title text adds to the ice-cream path the stipulation that you also carry an ice-cream to the target swimmer to 'justify' that choice of route. But how this squares with the reason to rendezvous with the swimmer, or the manner in which this would further complicate the swimming stage, goes unsaid. But it makes it clear that ''not'' doing this isn't considered socially permissible, whether or not he had stopped to eat an ice-cream of his own beforehand.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball stands on the beach, with another person in the water. Ponytail stands on the beach in an ice cream stand in the top right corner.]
:Path that minimizes distance [A straight line from beach cueball to ocean cueball, bearing about 135]
:Path that minimizes time [A line from beach cueball to the waterline closer to horizontal, bearing about 120, then angling towards ocean cueball, bearing about 150]
:Path that minimizes swimming [A line from beach cueball to the waterline closest to ocean cueball, bearing about 115, then angling toward ocean cueball, bearing 180]
:Path that minimizes time until you get ice cream [A line from beach cueball to the ice cream stand manned by Ponytail, bearing about 90, then angling toward ocean cueball, bearing about 190]
:Path that maximizes time [A line from beach cueball away from the shore, bearing 0, fading and disappearing at the top of the panel, and reappearing at the bottom of the panel directly below ocean cueball]

{{comic discussion}}

[[Category:Food]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Multiple Cueballs]]
[[Category:Physics]]

2821: Path Minimization

2023-08-31T00:26:31Z

Capybarafan436: /* Transcript */ Added the people.

{{comic
| number = 2821
| date = August 28, 2023
| title = Path Minimization
| image = path_minimization_2x.png
| imagesize = 562x559px
| noexpand = true
| titletext = Of course you get an ice cream cone for the swimmer too! You're not a monster.
}}

==Explanation==
{{incomplete|Created by WAITING AN HOUR BEFORE SWIMMING - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

In this comic, it appears that Cueball, standing on shore, is observing a swimmer who is possibly (but not obviously) in distress. The comic illustrates five potential paths that can be taken to reach the swimmer, each with a different reason to make them viable, in the manner of demonstrating different optimal strategies that can be chosen.

The first path is a direct line from Cueball, straight to the swimmer, which allows for the minimum possible distance to be traveled, some on land and the remainder in the water.

The second path travels more obliquely from Cueball to the water and then at a sharper angle to the swimmer. This path would take the shortest amount of time, presuming that Cueball would move faster on land (covering more of the distance) and slower through the water (but less distance). The exact angles would depend on how much faster Cueball is on land than in the water. The relationship between speeds and angles is the same as that in {{w|Snell's law}} for light passing between two media.

The third path travels at a far more oblique angle to the water, such that the subsequent swimming path is entirely perpendicular to the shoreline, adding to the amount of time spent on land in order to minimize the time spent swimming. Depending on one's swimming ability versus running ability, this could be the safest path to take. It might also be more sensible to keep the target in clear sight for as long as possible, from the land, then aim exactly away from shore when both your head and theirs are barely at wave-height (though currents may complicate this). But this is a completely different reason from the distance or time preferences.

The fourth path travels nearly parallel to the beach. In fact moving slightly ''away'' from the swimmer but towards an intermediate goal: an ice cream stand. After that, the path turns and aims straight towards the swimmer, as all the others eventually do (although it is not made clear at this point if Cueball will spend time eating his ice cream on the beach, or will attempt to carry and possibly eat an ice cream whilst swimming).

The fifth and final path, barely recognizable as a path, points off the top of the comic and reappears at the bottom. This path presumably travels around the entire world, likely stopping for many, ''many'' rest breaks. It is labeled as the path that ''maximizes'' time. It should be noted that, by the definition given, it is theoretically possible to stretch the maximum time taken out forever by simply walking away and never returning.

You could also fulfill the criteria of reaching the target in finite, but arbitrarily long, time by following a {{w|random walk}}(+swim) or even follow a {{w|space-filling curve}} carefully chosen to be the maximally finite scenario. Or you could simply choose any path, and stop for an arbitrarily long time, or travel at a speed approaching zero. In the comic, however, a requirement for simplicity of path may dictate the use of something close to the opposing {{w|great-circle distance}}, or a variation that has a maximal swim-time even without ''undue'' time-wasting detours, and assume equal speeds of travel on all routes.

The comic pokes fun at two famous physical/mathematical problems that are usually stated as happening on a beach. The first is the Lifeguard problem, used by Richard Feynman in his book ''QED'' to illustrate {{w|Fermat's principle}}, or principle of least time, which states that the path taken by a light ray between two given points is the path that can be traveled in the least time. This is closely related to {{w|Stationary-action principle}} for mechanical systems. In Feynman's words:

''"Finding the path of least time for light is like finding the path of least time for a lifeguard running and then swimming to rescue a drowning victim: the path of least distance has too much water in it; the path of least water has too much sand in it; the path of least time is a compromise between the two."'' - ''Richard Feynman, QED - The Strange Theory of Light and Matter (1988, Princeton University Press), Chapter 2.''

The second problem referenced in this comic is the [https://gametheory101.com/courses/game-theory-101/hotellings-game-and-the-median-voter-theorem Beach Vendor Problem], which is stated as follows. Suppose that on a long beach there are two ice cream vendors. Customers are uniformly distributed on the beach and each person will go get the ice cream at the closest vendor. Each vendor wants to maximize the number of customers that buy at their place. To minimize the customer's walking time, the optimal configuration would be to have one vendor at 1/4 of the beach length and the other at 3/4, but {{w|Hotelling's law}} predicts that the two shops will converge to the middle of the beach, in an attempt to steal as many customers as possible from the competition. This is a case of {{w|Nash equilibrium}} that is also related to the {{w|Median voter theorem}}. If the number of vendors is larger than 2, the problem may become [https://gametheory101.com/tag/hotellings-game/ considerably more complicated].

The title text adds the stipulation, to the ice-cream path, that you also carry an ice-cream to the target swimmer to 'justify' that choice of route. But how this squares with the reason to rendezvous with the swimmer, or the manner in which this would further complicate the swimming stage, goes unsaid. But it makes it clear that ''not'' doing this isn't considered socially permissible, whether or not he had stopped to eat an ice-cream of his own beforehand.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball stands on the beach, with another person in the water.]
:Path that minimizes distance [A straight line from beach cueball to ocean cueball, bearing about 135]
:Path that minimizes time [A line from beach cueball to the waterline closer to horizontal, bearing about 120, then angling towards ocean cueball, bearing about 150]
:Path that minimizes swimming [A line from beach cueball to the waterline closest to ocean cueball, bearing about 115, then angling toward ocean cueball, bearing 180]
:Path that minimizes time until you get ice cream [A line from beach cueball to an ice cream stand manned by Ponytail, bearing about 90, then angling toward ocean cueball, bearing about 190]
:Path that maximizes time [A line from beach cueball away from the shore, bearing 0, fading and disappearing at the top of the panel, and reappearing at the bottom of the panel directly below ocean cueball]

{{comic discussion}}

[[Category:Food]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Multiple Cueballs]]
[[Category:Physics]]