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

AVI file extension

Audio Video Interleave File

Video Files

CPP file extension

C++ Source Code File

Developer Files

DBF file extension

Database File

Database Files

DEB file extension

Debian Software Package

Compressed Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

GAM file extension

Saved Game File

Game Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

INDD file extension

Adobe InDesign Document

Layout Files

MP3 file extension

MP3 Audio File

Audio Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PPT file extension

PowerPoint Presentation

Data Files

SWF file extension

Shockwave Flash Movie

Video Files

TEX file extension

LaTeX Source Document

Text Files

VB file extension

VBScript File

Executable Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files