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

CRX file extension

Chrome Extension

Plugin Files

CS file extension

Visual C# Source Code File

Developer Files

GBR file extension

Gerber File

Data Files

INI file extension

Windows Initialization File

Settings Files

KMZ file extension

Google Earth Placemark File

GIS Files

LOG file extension

Log File

Text Files

MSG file extension

Outlook Mail Message

Text Files

PCT file extension

Picture File

Layout Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

SLN file extension

Visual Studio Solution File

Developer Files

SRT file extension

SubRip Subtitle File

Video Files

WPD file extension

WordPerfect Document

Text Files

XML file extension

XML File

Data Files