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

CAB file extension

Windows Cabinet File

System Files

CSS file extension

Cascading Style Sheet

Web Files

DB file extension

Database File

Database Files

H file extension

C/C++/Objective-C Header File

Developer Files

IFF file extension

Interchange File Format

Audio Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PNG file extension

Portable Network Graphic

Raster Image Files

TAR file extension

Consolidated Unix File Archive

Data Files

TEX file extension

LaTeX Source Document

Text Files

TORRENT file extension

BitTorrent File

Misc Files

TXT file extension

Plain Text File

Text Files

VCXPROJ file extension

Visual C++ Project

Developer Files

3DS file extension

3D Studio Scene

3D Image Files