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

BIN file extension

Binary Disc Image

Disk Image Files

FON file extension

Generic Font File

Font Files

GBR file extension

Gerber File

Data Files

WMA file extension

Windows Media Audio File

Audio Files

7Z file extension

7-Zip Compressed File

Compressed Files

OTF file extension

OpenType Font

Font Files

TAR file extension

Consolidated Unix File Archive

Data Files

M4V file extension

iTunes Video File

Video Files

CSR file extension

Certificate Signing Request File

Web Files

APK file extension

Android Package File

Executable Files

MDF file extension

Media Disc Image File

Disk Image Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

KML file extension

Keyhole Markup Language File

GIS Files

JAR file extension

Java Archive File

Executable Files

ASPX file extension

Active Server Page Extended File

Web Files