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

APP file extension

Mac OS X Application

Executable Files

CGI file extension

Common Gateway Interface Script

Executable Files

COM file extension

DOS Command File

Executable Files

CUE file extension

Cue Sheet File

Disk Image Files

DB file extension

Database File

Database Files

DMP file extension

Windows Memory Dump

System Files

GAM file extension

Saved Game File

Game Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

HTML file extension

Hypertext Markup Language File

Web Files

KML file extension

Keyhole Markup Language File

GIS Files

KMZ file extension

Google Earth Placemark File

GIS Files

LNK file extension

Windows File Shortcut

System Files

MID file extension

MIDI File

Audio Files

SAV file extension

Saved Game

Game Files

SDF file extension

Standard Data File

Data Files