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

7Z file extension

7-Zip Compressed File

Compressed Files

GED file extension

GEDCOM Genealogy Data File

Data Files

3DS file extension

3D Studio Scene

3D Image Files

FON file extension

Generic Font File

Font Files

PHP file extension

PHP Source Code File

Web Files

CGI file extension

Common Gateway Interface Script

Executable Files

DEM file extension

Video Game Demo File

Game Files

CUE file extension

Cue Sheet File

Disk Image Files

VCF file extension

vCard File

Data Files

TAR file extension

Consolidated Unix File Archive

Data Files

AIF file extension

Audio Interchange File Format

Audio Files

MPG file extension

MPEG Video File

Video Files

ASF file extension

Advanced Systems Format File

Video Files

CUR file extension

Windows Cursor

System Files

CSS file extension

Cascading Style Sheet

Web Files