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

COM file extension

DOS Command File

Executable Files

DXF file extension

Drawing Exchange Format File

CAD Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

ICS file extension

iCalendar File

Misc Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MSI file extension

Windows Installer Package

Misc Files

SDF file extension

Standard Data File

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

WPD file extension

WordPerfect Document

Text Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

3GP file extension

3GPP Multimedia File

Video Files