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

AIF file extension

Audio Interchange File Format

Audio Files

ASX file extension

Microsoft ASF Redirector File

Video Files

DDS file extension

DirectDraw Surface

Raster Image Files

GADGET file extension

Windows Gadget

Executable Files

ICO file extension

Icon File

System Files

ICS file extension

iCalendar File

Misc Files

ISO file extension

Disc Image File

Disk Image Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

MAX file extension

3ds Max Scene File

3D Image Files

MPA file extension

MPEG-2 Audio File

Audio Files

PPT file extension

PowerPoint Presentation

Data Files

RM file extension

Real Media File

Video Files

SAV file extension

Saved Game

Game Files

TOAST file extension

Toast Disc Image

Disk Image Files

UUE file extension

Uuencoded File

Encoded Files