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

AI file extension

Adobe Illustrator File

Vector Image Files

AIF file extension

Audio Interchange File Format

Audio Files

CSR file extension

Certificate Signing Request File

Web Files

CUE file extension

Cue Sheet File

Disk Image Files

DAT file extension

Data File

Data Files

ISO file extension

Disc Image File

Disk Image Files

LUA file extension

Lua Source File

Developer Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MPG file extension

MPEG Video File

Video Files

PKG file extension

Mac OS X Installer Package

Compressed Files

SQL file extension

Structured Query Language Data File

Database Files

TGA file extension

Targa Graphic

Raster Image Files

TIF file extension

Tagged Image File

Raster Image Files

WMA file extension

Windows Media Audio File

Audio Files

3DM file extension

Rhino 3D Model

3D Image Files