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

DLL file extension

Dynamic Link Library

System Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

EXE file extension

Windows Executable File

Executable Files

FLA file extension

Adobe Flash Animation

Developer Files

GAM file extension

Saved Game File

Game Files

H file extension

C/C++/Objective-C Header File

Developer Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

JPG file extension

JPEG Image

Raster Image Files

M file extension

Objective-C Implementation File

Developer Files

MPA file extension

MPEG-2 Audio File

Audio Files

PL file extension

Perl Script

Developer Files

TAR file extension

Consolidated Unix File Archive

Data Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

3DS file extension

3D Studio Scene

3D Image Files