What are file extensions used for?
Also know, what do file extensions do?
A file extension, sometimes called a file suffix or a filename extension, is the character or group of characters after the period that makes up an entire file name. The file extension helps an operating system, like Windows or macOS, determine which program on your computer the file is associated with.
In respect to this, why do we need file extensions?
The file extension allows computer users to quickly identify the nature of a file's contents. Users can group, sort or order files in a directory by file extension. This provides a simple method of keeping all files of the same type together, making searches through lists of files quicker.
The file extension is a three-letter code that appears at the end of a file name, although it is sometimes hidden (more about that in a minute). For example, if a file is named mythesis. doc, the . doc is the file extension, and it tells Windows that the file was created with Microsoft Word.