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

HTM file extension

Hypertext Markup Language File

Web Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

AIF file extension

Audio Interchange File Format

Audio Files

YUV file extension

YUV Encoded Image File

Raster Image Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

OTF file extension

OpenType Font

Font Files

TTF file extension

TrueType Font

Font Files

LUA file extension

Lua Source File

Developer Files

BAT file extension

DOS Batch File

Executable Files

3G2 file extension

3GPP2 Multimedia File

Video Files

CPP file extension

C++ Source Code File

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

AVI file extension

Audio Video Interleave File

Video Files

FNT file extension

Windows Font File

Font Files

TAR file extension

Consolidated Unix File Archive

Data Files