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

AVI file extension

Audio Video Interleave File

Video Files

BMP file extension

Bitmap Image File

Raster Image Files

CUE file extension

Cue Sheet File

Disk Image Files

EXE file extension

Windows Executable File

Executable Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

ODT file extension

OpenDocument Text Document

Text Files

PART file extension

Partially Downloaded File

Misc Files

PIF file extension

Program Information File

Executable Files

PPT file extension

PowerPoint Presentation

Data Files

RTF file extension

Rich Text Format File

Text Files

SYS file extension

Windows System File

System Files

TORRENT file extension

BitTorrent File

Misc Files

3G2 file extension

3GPP2 Multimedia File

Video Files