File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

AVI file extension

Audio Video Interleave File

Video Files

AZW file extension

Amazon Kindle eBook File

eBook Files

CSV file extension

Comma Separated Values File

Data Files

CUE file extension

Cue Sheet File

Disk Image Files

DAT file extension

Data File

Data Files

DEM file extension

Video Game Demo File

Game Files

GAM file extension

Saved Game File

Game Files

ICO file extension

Icon File

System Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

MID file extension

MIDI File

Audio Files

RA file extension

Real Audio File

Audio Files

SH file extension

Bash Shell Script

Developer Files

THM file extension

Thumbnail Image File

Raster Image Files

TIF file extension

Tagged Image File

Raster Image Files

TMP file extension

Temporary File

Backup Files