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

CPP file extension

C++ Source Code File

Developer Files

CRX file extension

Chrome Extension

Plugin Files

CSS file extension

Cascading Style Sheet

Web Files

DEB file extension

Debian Software Package

Compressed Files

GAM file extension

Saved Game File

Game Files

JS file extension

JavaScript File

Web Files

KEY file extension

Keynote Presentation

Data Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

M4V file extension

iTunes Video File

Video Files

MOV file extension

Apple QuickTime Movie

Video Files

MSG file extension

Outlook Mail Message

Text Files

SQL file extension

Structured Query Language Data File

Database Files

TAR file extension

Consolidated Unix File Archive

Data Files

TORRENT file extension

BitTorrent File

Misc Files

YUV file extension

YUV Encoded Image File

Raster Image Files