Did you know that at one point, Microsoft restricted the file extension to just three characters? What that means is, files like .torrent stood no chance of running on a MS OS like Windows. This has changed since, and thanks to sites like www.file-extension.com, we can now track the progress and purpose of even the lesser know file extensions.
A precise outline of the nature and function of file extensions is not as simple as one would image, with over 40 years of developments and competing influences of Mac, Windows/Dos, and Unix-like operating systems, file systems and metadata formats are now harder to recognize and in some instances trust.
Three of the most popular type of files downloaded frequently online are probably the file extension MP3, GZ files and Zip. My personal favorite is the versatile MP3s, which are commonly used to encode audio with an intentionally simple algorithm specifically designed to maximize compression whilst still reproducing an audio track that sounds faithful to the original. Not only are these files versatile, they can be played with most all audio players.
Back to the File Extension site, I found that neither UNIX nor Mac operating systems used file extensions when they started rolling out. Instead each had their own file systems, with different conventions for storing metadata, which thankfully has changed over time. If you think you have see it all, check the site and you will realize that there are thousands of extensions you have used and many we will never. And when you do run into questions, you can count on file-extension.com to help you out.