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

TAR file extension

Consolidated Unix File Archive

Data Files

ACCDB file extension

Access 2007 Database File

Database Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

COM file extension

DOS Command File

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

VCD file extension

Virtual CD

Disk Image Files

CER file extension

Internet Security Certificate

Web Files

CS file extension

Visual C# Source Code File

Developer Files

APP file extension

Mac OS X Application

Executable Files

M4V file extension

iTunes Video File

Video Files

VCXPROJ file extension

Visual C++ Project

Developer Files

PCT file extension

Picture File

Layout Files

M3U file extension

Media Playlist File

Audio Files

ZIP file extension

Zipped File

Compressed Files

DEM file extension

Video Game Demo File

Game Files