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

ASX file extension

Microsoft ASF Redirector File

Video Files

AVI file extension

Audio Video Interleave File

Video Files

CPP file extension

C++ Source Code File

Developer Files

DEM file extension

Video Game Demo File

Game Files

DLL file extension

Dynamic Link Library

System Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

GAM file extension

Saved Game File

Game Files

GBR file extension

Gerber File

Data Files

ICO file extension

Icon File

System Files

M file extension

Objective-C Implementation File

Developer Files

PL file extension

Perl Script

Developer Files

PRF file extension

Outlook Profile File

Settings Files

TARGZ file extension

Compressed Tarball File

Compressed Files

TOAST file extension

Toast Disc Image

Disk Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files