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

AIF file extension

Audio Interchange File Format

Audio Files

BAK file extension

Backup File

Backup Files

COM file extension

DOS Command File

Executable Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

GPX file extension

GPS Exchange File

GIS Files

H file extension

C/C++/Objective-C Header File

Developer Files

ICS file extension

iCalendar File

Misc Files

KEY file extension

Keynote Presentation

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

LNK file extension

Windows File Shortcut

System Files

M file extension

Objective-C Implementation File

Developer Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RM file extension

Real Media File

Video Files

WMV file extension

Windows Media Video File

Video Files