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

CUR file extension

Windows Cursor

System Files

DEM file extension

Video Game Demo File

Game Files

DMP file extension

Windows Memory Dump

System Files

FON file extension

Generic Font File

Font Files

GBR file extension

Gerber File

Data Files

IFF file extension

Interchange File Format

Audio Files

INDD file extension

Adobe InDesign Document

Layout Files

M4V file extension

iTunes Video File

Video Files

PNG file extension

Portable Network Graphic

Raster Image Files

RTF file extension

Rich Text Format File

Text Files

SYS file extension

Windows System File

System Files

TIF file extension

Tagged Image File

Raster Image Files

TMP file extension

Temporary File

Backup Files

WMV file extension

Windows Media Video File

Video Files