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

CBR file extension

Comic Book RAR Archive

Compressed Files

CS file extension

Visual C# Source Code File

Developer Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

FLA file extension

Adobe Flash Animation

Developer Files

GPX file extension

GPS Exchange File

GIS Files

H file extension

C/C++/Objective-C Header File

Developer Files

ICO file extension

Icon File

System Files

M4A file extension

MPEG-4 Audio File

Audio Files

PART file extension

Partially Downloaded File

Misc Files

SITX file extension

StuffIt X Archive

Compressed Files

SRT file extension

SubRip Subtitle File

Video Files

TGA file extension

Targa Graphic

Raster Image Files

TXT file extension

Plain Text File

Text Files

ZIPX file extension

Extended Zip File

Compressed Files

3DM file extension

Rhino 3D Model

3D Image Files