Footer comics
The footer comics are likely selected for representing the topics covered on xkcd. These comics can be often described as heavily representational of the comic itself. They are:
150: Grownups | 730: Circuit Diagram | 162: Angular Momentum | 688: Self-Description | 556: Alternative Energy Revolution |
1732: Earth Temperature Timeline |
On February 7, 2006 the first footer comics were available. It featured 40, 49, 37, 44 & 10, in that order.
- On April 8, 2006 the first one changed to 77.
- On October 13, 2006 it changed to current style, although still only the five top footer comics, and with 150, 123, 162, 55 & 77, rather than the current set of five.
- On August 17, 2010 it changed three of the comics leaving 150, 730, 162, 688, 556. Those five are all still there.
- On March 1, 2019 it changed to the current version by including 1732: Earth Temperature Timeline below the other five comics. The new addition was included as one long image taking up the same space as the other five comics.