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

CFG file extension

Configuration File

Settings Files

CSS file extension

Cascading Style Sheet

Web Files

DLL file extension

Dynamic Link Library

System Files

DOC file extension

Microsoft Word Document

Text Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

GBR file extension

Gerber File

Data Files

LUA file extension

Lua Source File

Developer Files

M4A file extension

MPEG-4 Audio File

Audio Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MPA file extension

MPEG-2 Audio File

Audio Files

PCT file extension

Picture File

Layout Files

SAV file extension

Saved Game

Game Files

TIF file extension

Tagged Image File

Raster Image Files

ZIPX file extension

Extended Zip File

Compressed Files

3GP file extension

3GPP Multimedia File

Video Files