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

CFM file extension

ColdFusion Markup File

Web Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

GAM file extension

Saved Game File

Game Files

IFF file extension

Interchange File Format

Audio Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

ROM file extension

N64 Game ROM File

Game Files

SYS file extension

Windows System File

System Files

TEX file extension

LaTeX Source Document

Text Files

TGA file extension

Targa Graphic

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

XCODEPROJ file extension

Xcode Project

Developer Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

3DS file extension

3D Studio Scene

3D Image Files