1301: File Extensions

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File Extensions

Title text: I have never been lied to by data in a .txt file which has been hand-aligned.

Explanation

Almost all file names end in a period followed by a (generally three-letter) suffix known as a file extension, used to determine the type of content contained in the file. Generally (but not always), a particular extension will only be used by a specific program or small set of programs, making a file's extension a quick indicator of how the file might have been produced.

Because of that last part, and the fact that certain programs will tend to be used by only certain types of people, a file's extension may provide a hint toward how trustworthy the file's content may be.

• .tex files are TeX and LaTeX source files; the aforementioned programs are often and almost exclusively used by academics, especially in mathematics and the hard sciences. .tex means serious business.
• .pdf files are a document format by Adobe, frequently used for publication. Thus, a .pdf file is likely to be some type of final product or polished work.
• .csv files contain a bunch of raw data delimited by commas, and are likely computer-generated (from, say, a scientific experiment).
• .txt files contain only plain text, no "rich text" or anything fancy. They are generally used by programmers for purposes such as README files.
• .svg files are a vector graphics format used a lot for diagrams, such as on Wikipedia.
• .xls and .xlsx are spreadsheets. .xls (.xlsx since 2007) is a proprietary format used by Microsoft Excel as part of the Microsoft Office bundle and .xlsx is an Office Open XML format created by Microsoft. Anyone with Microsoft Office (very popular among Windows Users) could easily make one of these. The files stereotypically contain a mix of raw data (similar to a .csv) and calculations and plots using that data.
• .doc is another proprietary document format, used by Microsoft Word, also part of the Microsoft Office bundle. A good portion of Windows users have Microsoft Office, and any one of them could easily make one of these (probably why Randall doesn't trust it much).
• .png is a bitmap image format designed for the Internet. It is enjoying wide popularity for providing crisp, full-color images with lossless (invisible) compression. Almost all xkcd comics, this diagram included, use PNG. Self-deprecation, maybe?
• .ppt refers to a Microsoft Office Powerpoint file. Again, anyone with Windows can make one of these, but they are usually used for presentations, not documents. Thus, the information will be arranged differently, possibly to "dumb down" the content.
• .jpg and jpeg are the same and used as an image format with high compression capabilities, excellent for storing photos, but not so good for many other things. This file format is prone to annoying compression artifacts; storing numerical or textual information in a JPEG file is typically a bad idea. Digital cameras use JPEG compression while the original .raw could be up to hundred times larger. Therefore, you can't trust the content of a JPEG file, because it doesn't contain the original content. Further, there is also the possibility that viruses can get embedded into JPEG files. The extension .jpeg is less trustworthy than .jpg as it does not conform to the three letter rule for file extension suffixes, implying the creator is not very tech-savvy.
• .gif is a bitmap image format capable of short animations. It was once the Internet image file format until PNG gradually replaced it for many good reasons. It made a comeback in recent years, mostly for silly clips of cats falling into boxes. It's also used in blinking ads claiming that you're the 570,000th VISITOR!, and in the online adult industry for both content and marketing. In addition, because it can be animated, people will often make seemingly normal images that then have something pop out and startle you.

Most of the Microsoft file formats can also be created using open source programs such as Open Office or Libre Office; unlike Microsoft Office applications these are also available for Linux. There also exist apps for Android tablets that can edit Microsoft file formats.

The title text refers to some plain text editors, producing simple .txt files, where the human editor and not the application is resposible for aligning the text. Proper indents are one method to improve the text for a human reader on such a plain text file.

Transcript

Trustworthiness of Information by File Extension

[A bar graph charting this. No units or figures are given, but for ease of comprehension this transcript will arbitrarily designate the highest score as "+100"; subsequent scores are estimates based on the size of their bars.]

.tex: +100

.pdf: +89

.csv: +85

.txt: +67

.svg: +65

.xls/.xlsx: +49

.doc: +21

.png: +15

.ppt: +14

.jpg: +3

.jpeg: -8

.gif: -36

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Discussion

Tex is a Turing complete language so when it compiles to a PDF it could hide malicious code. 141.101.98.154 (talk) 13:16, 29 September 2017 (UTC) (please sign your comments with ~~~~)

No, that's wrong! Turing-completeness refers to what calculations a system can perform; it doesn't say anything about how an implementation of that system can interact with another system that hosts it. Conway's Game of Life is Turing-complete, but you'd never imagine a Life board to be an attack vector. (Now, if your TeX compiler has a vulnerability, that's another issue.) 162.158.74.87 13:18, 19 August 2019 (UTC)

The title text reference of "hand-aligned data" may refer to ASCII art. 108.162.215.28 05:36, 9 December 2013 (UTC) Alan K.

I'd think not, given that art isn't exactly data. My guess would be tables in the .txt - a .txt file is just raw text with no formatting, so putting a table in requires manually formatting it with a bunch of spaces/tabs. It's not hard, but can be time-consuming and obnoxious. 108.162.219.47 23:57, 10 December 2013 (UTC)

Any programmer would tell you to never try and hand-align things with tabs. Different text editors will use anything from 3 to 8 spaces for a tab, meaning that what's aligned in your editor isn't in others. 108.162.236.13 (talk) 14:09, 21 December 2013 (UTC) (please sign your comments with ~~~~)

Indent with tabs; align with spaces. More formally, tabs should only be at the beginning of a line, and should have a strong contextual relationship with the surrounding text. This is a reasonably thought out explanation: http://lea.verou.me/2012/01/why-tabs-are-clearly-superior/ 199.27.128.67 17:18, 19 February 2014 (UTC)

I think it's also a notable point, that the better rated document formats are more data centric while the low rated formats mix text informations with design elements and finally become pure graphic formats, which often is an indication, that the author didn't use the accurate file type for (mostly) pure text informations.

Something I don't understand is the gap between jpg and jpeg. The first suffix is AFAIK only an abbreviation used by older DOS/MS Systems to fullfill the 8.3 limitation for filenames. The note about hand alignment might concern the fact, that hand alignment is more time expensive which might increase the amount of the the author spend in overthink the content before layouting. Also often automated layouting as supported by many modern writing application might lead to unexpected and sometimes wrong results, because the automatism has no semantical knowledge about the authors intention, which might lead to post processed errors

Sorry for my bad english, I'm not a natural writer 108.162.231.239 05:45, 9 December 2013 (UTC)

"hand-aligned data" seems to me like (manually) space-indented paragraphs, perhaps even manual padding to achieve the desired justification (centering and right-and-left-margin-hugging). And of course neatly lining up an 'embedded table', perhaps originally extracted from a .csv output. Although a number of plain-text editors (in the days of CGA and pure terminal/fixedspace fonts) or text formatters and wrappers (e.g. Lynx, man-page creaters, etc) would do things like this for you. And still do. At least insofar as the justification and margining is concerned. 141.101.99.229 08:35, 9 December 2013 (UTC)

If anyone has taken the time to hand align a text file (as in a README, or other info file), they want it to look attractive for people to read. Odd are you're not going to take the time to "hand pretty" the document just to be malicious. Back in the BBS days there were a large number of "online" groups who had "signature" text files which were (very probably) hand aligned, and made extensive use of extended ASCII codes to generate basic graphics. (Granted there were programs to help auto-generate "ascii art".) If you've ever seen these files you'd know. Example 1 - Example 2 Jarod997 (talk) 14:14, 9 December 2013 (UTC)

I thought hand aligned meant an image of a .txt file that was hand-rotated, kinda like the .NORM file joke.172.70.110.65 18:00, 19 March 2022 (UTC)Bumpf

I find it interesting that .jpg and .jpeg are at different levels. Aren't those the same thing? --Mralext20 (talk) 05:48, 9 December 2013 (UTC)

Perhaps the .gif could contain suddenly unexpected scary/surprising frames? 108.162.208.172 14:54, 9 December 2013 (UTC)

That JPG/JPEG thing indeed seems strange. The more important distinction is between JPEGs that are photographs (fine) and those that are not (stupid). Also, pre-PNG, non-photograph GIFs could be just fine. And with all the accounting scandals we've seen, why would those spreadsheet formats get any credibility? -- Dfeuer (talk) 06:06, 9 December 2013 (UTC)

Alongside .jpeg ('full' extension format) and .jpg (MS '8.3'-compatible extension format), I'd have expected .jpe (often full extension historically truncated on an 8.3 system), I must be honest. (And interesting that .docx doesn't co-inhabit the .doc line... or be somewhere else.) And the disparity betwixt the two versions of JPEG extension may relate to the tendency for a higher artefact-intensity of images back in the early days (when a better option than GIFs for... certain pictures... e.g. on Usenet between *nix workstations with vastly restricted bandwidths and storage capacities) compared to today's users (cameras that regularly store 10+MP pictures in low-loss JFIF files, and/or in Raw format!). But that may be a spurious or off-track reasoning on my part. 141.101.99.229 08:27, 9 December 2013 (UTC)

I measured the bars in photoshop to +/- 2pixels. If we scale .tex to a value of 100 like the transcript says, these are the values I get for the bar lengths (rounded to one decimal place)

• .tex: 100
• .pdf: 89.4
• .csv: 84.9
• .txt: 66.5
• .svg: 64.8
• .xls: 48.6
• .doc: 21.2
• .png: 15.1
• .ppt: 14.5
• .jpg: 3.4
• .jpeg: -8.4
• .gif: -35.8

Dunno if it is helpful - or even trusted given I'm a first time commenter - but there it is. Closer values than just estimating, though the eyeballed estimates aren't bad. Not going to adjust the actual transcript because I feel that's overstepping my bounds. 108.162.216.56 (talk) 07:34, 9 December 2013 (UTC) (please sign your comments with ~~~~)

Not at all, wikis are free to edit for a reason. If we didn't want new users to be editing pages, we could have turned that off long ago. Davidy²²[talk] 07:55, 9 December 2013 (UTC)

As the information that is provided by the graph comes as png, we should probably not trust her. --141.101.92.120 09:03, 9 December 2013 (UTC)

Ha, +1 Like :-) Spongebog (talk) 14:02, 9 December 2013 (UTC)

I never saw image of cute cats lying to me ... I mean, the gif is STILL the preferred format for animation, mostly because it's the only one supported. Animation formats based on PNG didn't catched up, hard to say why ... on the other hand, gif animation apparently have huge number of weird extensions, judging by the number of animated images I found which don't render properly in anything EXCEPT the browser. -- Hkmaly (talk) 10:27, 9 December 2013 (UTC)

The cute cat may not be lying, but since the format is used in other context -- like banner ads, then the average GIF may well be lying, also I believe there have been many security issues with GIFs and JPGs as they have been used as an attack vector for internet-bad-guys to take over your computer -- so while security issues is not specifically the topic for todays strip, then that may be worth noticing as well Spongebog (talk) 14:02, 9 December 2013 (UTC)

It is also possible to create animations with svg which is (for good reason, I like that format) ranked higher. Especially for scientific purposes it can be handy. Unfortunately is the MediaWiki software unable to show them. For example in the previous comic is an animation of the Galilean moons shown. That is an gif but someone also uploaded an svg animation and I would say it does look smoother than the gif. 108.162.231.215 14:40, 9 December 2013 (UTC)

The Grumpy Cat is not grumpy in real life - so cat pictures DO lie! Schmammel (talk) 15:40, 9 December 2013 (UTC)

What is the scale of the chart? Does 'top' = most trusted'? Never assume anything with xkcd. David.windsor (talk) 18:29, 9 December 2013 (UTC)

Brilliant. I didn't think of that at all. But now that you mention it... a .gif would be like a small part of a video. And people tend to trust those more than a static picture. 108.162.222.209 08:58, 13 December 2013 (UTC)

Of course Randall does not really think that the file extension determines trustworthiness; the graph is tongue-in-cheek. Information can be trustworthy or untrustworthy no matter the format it's given in. 108.162.216.221 18:50, 9 December 2013 (UTC)

Yes, I believe the explanation somewhat misinterprets Randall's intentions, especially when it comes to the image formats. I interpret it not as a question of loss of information due to compression but instead a more general impression of when and by whom these formats are used and, as a consequence, the trustworthiness of the information conveyed through these formats. That would explain the jpg/jpeg distinction as (in my experience though I can't provide data that support it) .jpg is nowadays the preferred compressed format in professional contexts and .jpeg looks slightly childish. 141.101.80.117 23:59, 9 December 2013 (UTC)

Reading more into the linked info about viruses embedded in JPEGs, it appears that the only way to receive a virus from a JPEG file would be to have already received another virus from a standard executable file, where such a virus causes the computer to execute code in a JPEG file rather than simply display it as it normally would. Since such a possibility is independent of the file type (the first virus might just as well have enabled code execution in DOC files, for instance), I've removed that bit of info. Zowayix (talk) 03:44, 10 December 2013 (UTC)

Can anyone explain the banner near the top of xkcd.com today, 10 Dec 2013? It reads, Dear Wikipedia readers: if everyone reading this showed up at my house, I would be like "what?" 108.162.219.220 (talk) 15:53, 10 December 2013 (UTC) (please sign your comments with ~~~~)

I believe that is a reference to the similar banner that is on top of wikipedia right now asking for donations. --Jeff (talk) 18:02, 10 December 2013 (UTC)

I don't see that banner, but it appears to be a play on Wikipedia's donation "pleas" that are often posted (including now) as banners at the top of Wikipedia which suggest that (to use the lates one:) "If everyone reading this donated, our fundraiser would be done within an hour". TheHYPO (talk) 18:05, 10 December 2013 (UTC)

I think it's a bit ambiguous whether Randall's references (for example) to jpg and gif means he doesn't trust that the images are accurate because of artifacting and stuff, or whether he's referring to jpgs and gifs that occasionally circulate with text on them as if to present information (e.g., lifehack images, or cat memes...) TheHYPO (talk) 18:05, 10 December 2013 (UTC)

missing suffices

Obviously .html & .htm are so far to the left, they're off the chart. :-) 108.162.249.117 17:43, 10 December 2013 (UTC)

Any idea what file type was used to spread this hoax? http://www.dailydot.com/lifestyle/apple-secret-bitcoin-mining-feature/ Various websites reporting on it use .JPG and .PNG, but I don't know what format the original graphic was. InspectorClouseau (talk) 16:16, 17 December 2013 (UTC)

I'd be pretty wary of .flv... Nick Douglas (talk) 15:16, 18 December 2013 (UTC)

I don't completely agree with ".png"'s explanation: "But since he rates the format so low, is Randall saying we shouldn't trust this chart?" I think it's being seen from the wrong perspective. In my opinion, ".png" is rated low due to being less capable and less commonly used to transmit trustworthy information than those rated higher. What do you all think? If you agree with me, please edit it, as I will not monitor this page.

I also think that ".tex"'s explanation is lacking. It should be said it's a way to format text documents using programming, in order to make them better looking and easier (for some) to write and format.

Plus, I generally disagree with a lot of what is said about file extensions, since our whole operating systems could work just fine if all extensions disappeared (provided that programs look for the right files by name only, and maybe a few more folders where created). But that's my own opinion, and not something to be added here. 108.162.219.125 02:57, 6 February 2015 (UTC)

One thing that seems to be overlooked here, is that GIFs are probably the least trustworthy because they can have those pop out horror images that scare you when you think you are just looking at a normal picture. 199.27.128.120 17:32, 20 April 2015 (UTC)

Funny story related to the trustworthiness of files, The other day a friend asked me "How do you make a jpg with transparency?" I said, "you can't." He sent me the file, sure enough it looked like a .jpg with transparency, it opened in windows pictures, in chrome, in firefox, however it wouldn't load in Gimp and it wouldn't load in Photoshop. I popped it into a file analyzer and it registered as a gif! So, yeah, gifs are pretty shady... 172.68.58.107 16:42, 11 September 2017 (UTC) Sam

Here's an entire Whitepaper written in a .txt file. If this isn't what this comic is trying to explain, I don't know what. http://www.linux-kvm.org/downloads/lersek/ovmf-whitepaper-c770f8c.txt?fbclid=IwAR1JnAtCs5syKoF70I0d-KnZpI3BnsceIRrCDgevCGrbVSejVThaKNlHDc0 172.69.44.152 (talk) 16:38, 15 June 2019 (UTC) (please sign your comments with ~~~~)