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

BAT file extension

DOS Batch File

Executable Files

C file extension

C/C++ Source Code File

Developer Files

DOC# file extension

Microsoft Word Document

Text Files

FLV file extension

Flash Video File

Video Files

ICO file extension

Icon File

System Files

LUA file extension

Lua Source File

Developer Files

MOV file extension

Apple QuickTime Movie

Video Files

MPA file extension

MPEG-2 Audio File

Audio Files

RA file extension

Real Audio File

Audio Files

SITX file extension

StuffIt X Archive

Compressed Files

TTF file extension

TrueType Font

Font Files

VCF file extension

vCard File

Data Files

VOB file extension

DVD Video Object File

Video Files

3DM file extension

Rhino 3D Model

3D Image Files