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

XCODEPROJ file extension

Xcode Project

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

OTF file extension

OpenType Font

Font Files

M4V file extension

iTunes Video File

Video Files

VCF file extension

vCard File

Data Files

TEX file extension

LaTeX Source Document

Text Files

CFM file extension

ColdFusion Markup File

Web Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

MAX file extension

3ds Max Scene File

3D Image Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

MDF file extension

Media Disc Image File

Disk Image Files

KMZ file extension

Google Earth Placemark File

GIS Files

XML file extension

XML File

Data Files

M3U file extension

Media Playlist File

Audio Files

ROM file extension

N64 Game ROM File

Game Files