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

ASF file extension

Advanced Systems Format File

Video Files

C file extension

C/C++ Source Code File

Developer Files

DEB file extension

Debian Software Package

Compressed Files

DEM file extension

Video Game Demo File

Game Files

DLL file extension

Dynamic Link Library

System Files

IFF file extension

Interchange File Format

Audio Files

M3U file extension

Media Playlist File

Audio Files

PHP file extension

PHP Source Code File

Web Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

RM file extension

Real Media File

Video Files

SLN file extension

Visual Studio Solution File

Developer Files

TIFF file extension

Tagged Image File Format

Raster Image Files

ZIPX file extension

Extended Zip File

Compressed Files

3DM file extension

Rhino 3D Model

3D Image Files

3GP file extension

3GPP Multimedia File

Video Files