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

CGI file extension

Common Gateway Interface Script

Executable Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

ICO file extension

Icon File

System Files

JAR file extension

Java Archive File

Executable Files

MDB file extension

Microsoft Access Database

Database Files

MSG file extension

Outlook Mail Message

Text Files

PAGES file extension

Pages Document

Text Files

SAV file extension

Saved Game

Game Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TMP file extension

Temporary File

Backup Files

TXT file extension

Plain Text File

Text Files

WMV file extension

Windows Media Video File

Video Files

XML file extension

XML File

Data Files

ZIPX file extension

Extended Zip File

Compressed Files