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

BAK file extension

Backup File

Backup Files

BAT file extension

DOS Batch File

Executable Files

CLASS file extension

Java Class File

Developer Files

CPP file extension

C++ Source Code File

Developer Files

DEM file extension

Video Game Demo File

Game Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DMP file extension

Windows Memory Dump

System Files

DXF file extension

Drawing Exchange Format File

CAD Files

ICO file extension

Icon File

System Files

PL file extension

Perl Script

Developer Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

SH file extension

Bash Shell Script

Developer Files

SLN file extension

Visual Studio Solution File

Developer Files

3DM file extension

Rhino 3D Model

3D Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files