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

M4V file extension

iTunes Video File

Video Files

VOB file extension

DVD Video Object File

Video Files

FON file extension

Generic Font File

Font Files

7Z file extension

7-Zip Compressed File

Compressed Files

M4A file extension

MPEG-4 Audio File

Audio Files

VB file extension

VBScript File

Executable Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

AVI file extension

Audio Video Interleave File

Video Files

GAM file extension

Saved Game File

Game Files

CS file extension

Visual C# Source Code File

Developer Files

ASP file extension

Active Server Page

Web Files

HTML file extension

Hypertext Markup Language File

Web Files

KMZ file extension

Google Earth Placemark File

GIS Files

DTD file extension

Document Type Definition File

Developer Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files