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

CFM file extension

ColdFusion Markup File

Web Files

CUR file extension

Windows Cursor

System Files

DB file extension

Database File

Database Files

DEM file extension

Video Game Demo File

Game Files

DXF file extension

Drawing Exchange Format File

CAD Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

ICNS file extension

Mac OS X Icon Resource File

System Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

KMZ file extension

Google Earth Placemark File

GIS Files

MPG file extension

MPEG Video File

Video Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SITX file extension

StuffIt X Archive

Compressed Files

THM file extension

Thumbnail Image File

Raster Image Files

WAV file extension

WAVE Audio File

Audio Files

WMA file extension

Windows Media Audio File

Audio Files