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

TTF file extension

TrueType Font

Font Files

ICS file extension

iCalendar File

Misc Files

CLASS file extension

Java Class File

Developer Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

RM file extension

Real Media File

Video Files

FLA file extension

Adobe Flash Animation

Developer Files

VB file extension

VBScript File

Executable Files

KML file extension

Keyhole Markup Language File

GIS Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

GZ file extension

Gnu Zipped Archive

Compressed Files

RA file extension

Real Audio File

Audio Files

7Z file extension

7-Zip Compressed File

Compressed Files

ICNS file extension

Mac OS X Icon Resource File

System Files

COM file extension

DOS Command File

Executable Files

AIF file extension

Audio Interchange File Format

Audio Files