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

BAT file extension

DOS Batch File

Executable Files

CUE file extension

Cue Sheet File

Disk Image Files

DAT file extension

Data File

Data Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

IFF file extension

Interchange File Format

Audio Files

INI file extension

Windows Initialization File

Settings Files

KML file extension

Keyhole Markup Language File

GIS Files

KMZ file extension

Google Earth Placemark File

GIS Files

M4V file extension

iTunes Video File

Video Files

MOV file extension

Apple QuickTime Movie

Video Files

PRF file extension

Outlook Profile File

Settings Files

RM file extension

Real Media File

Video Files

SITX file extension

StuffIt X Archive

Compressed Files

TORRENT file extension

BitTorrent File

Misc Files

TXT file extension

Plain Text File

Text Files