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

APP file extension

Mac OS X Application

Executable Files

AVI file extension

Audio Video Interleave File

Video Files

CFM file extension

ColdFusion Markup File

Web Files

DMP file extension

Windows Memory Dump

System Files

GBR file extension

Gerber File

Data Files

JSP file extension

Java Server Page

Web Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

MDB file extension

Microsoft Access Database

Database Files

PART file extension

Partially Downloaded File

Misc Files

RA file extension

Real Audio File

Audio Files

RM file extension

Real Media File

Video Files

SLN file extension

Visual Studio Solution File

Developer Files

TIF file extension

Tagged Image File

Raster Image Files

WPD file extension

WordPerfect Document

Text Files