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

APP file extension

Mac OS X Application

Executable Files

C file extension

C/C++ Source Code File

Developer Files

CLASS file extension

Java Class File

Developer Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DRV file extension

Device Driver

System Files

MAX file extension

3ds Max Scene File

3D Image Files

MOV file extension

Apple QuickTime Movie

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PIF file extension

Program Information File

Executable Files

PPS file extension

PowerPoint Slide Show

Data Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

TAR file extension

Consolidated Unix File Archive

Data Files

THM file extension

Thumbnail Image File

Raster Image Files

VCF file extension

vCard File

Data Files

XCODEPROJ file extension

Xcode Project

Developer Files