What Is The File Type Extension?

The File Type Extension of a file should not be mistaken for the actual file type. The extension merely serves as an identifier of a file in the form of a two to four letter suffix that is attached to the file name, separated by a period. The extension serves as an indication of the actual File Type and shows the user what kind of file (e.g. image, video, document) it is and which program should be used to open it.

Some and especially older operation systems only allowed for file extensions of three letters (e.g. .mp3), but file extensions with two (e.g. .ai) or four letters (e.g. .m3u8) can be found as well. Since the File Type Extension is usually separated from the file name by a period, this special character should not be used in the file name. Otherwise, the device might not be able to interpret the file correctly any more.

It is not advised to change the file extension manually, even though this is possible on most computers. Some systems may require to enable the display of file extensions before they can be seen as well.