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

APK file extension

Android Package File

Executable Files

C file extension

C/C++ Source Code File

Developer Files

CGI file extension

Common Gateway Interface Script

Executable 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

ICO file extension

Icon File

System Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

RA file extension

Real Audio File

Audio Files

SDF file extension

Standard Data File

Data Files

TGA file extension

Targa Graphic

Raster Image Files

XCODEPROJ file extension

Xcode Project

Developer Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

ZIP file extension

Zipped File

Compressed Files

3GP file extension

3GPP Multimedia File

Video Files