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

AVI file extension

Audio Video Interleave File

Video Files

C file extension

C/C++ Source Code File

Developer Files

CPL file extension

Windows Control Panel Item

System Files

CRX file extension

Chrome Extension

Plugin Files

CSV file extension

Comma Separated Values File

Data Files

DEB file extension

Debian Software Package

Compressed Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

JPG file extension

JPEG Image

Raster Image Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

MOBI file extension

Mobipocket eBook

eBook Files

ODT file extension

OpenDocument Text Document

Text Files

PCT file extension

Picture File

Layout Files

PNG file extension

Portable Network Graphic

Raster Image Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TEX file extension

LaTeX Source Document

Text Files