“A vicious circle of incompatibility”

A fun 16-minute video from PortalRunner with this premise: This is an image file, containing a picture of my cat. But if I rename it to .MP4, it becomes a video file – also of my cat. If rename to .PDF, it becomes a text document containing the script for this video. It can also be a valid webpage, a .ZIP archive, or a PowerPoint presentation, all by simply changing the name. This kind of file is sometimes called a “polyglot” (although, usually that term refers to code that works in multiple programming languages). This kind of a file is not something that you will realistically need, but it’s a fun look into various approaches to headers and structures of file formats – something we don’t usually get to think about a lot. Buried inside the video is also an interesting digression: is the file extension just a method of delivering the file to the right application? If I rename .jpeg to .gif, and both are routed to Pixelmator, should Pixelmator do its best to detect it’s a JPEG file…