Page "Filename extension" Paragraph 7

The filename extension was originally used to easily determine the file's generic type.

The need to condense a file's type into three characters frequently led to inscrutable extensions.

Examples include using for graphics files, for plain text, and for music.

However, because many different software programs have been made that all handle these data types ( and others ) in a variety of ways, filename extensions started to become closely associated with certain products — even specific product versions.

For example, early WordStar files used or, where n was the program's version number.

Also, filename extensions began to conflict between separate files.

One example is, used for both RPM Package Manager packages and RealPlayer Media files ; others being, shared by DESQview fonts, Quicken financial ledgers, and QuickTime pictures, and, shared between GrabIt scripts and Game Boy Advance ROM images.