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

SLN file extension

Visual Studio Solution File

Developer Files

WMV file extension

Windows Media Video File

Video Files

M file extension

Objective-C Implementation File

Developer Files

M4A file extension

MPEG-4 Audio File

Audio Files

AIF file extension

Audio Interchange File Format

Audio Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

ICS file extension

iCalendar File

Misc Files

CLASS file extension

Java Class File

Developer Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

FON file extension

Generic Font File

Font Files

GAM file extension

Saved Game File

Game Files

WAV file extension

WAVE Audio File

Audio Files

DXF file extension

Drawing Exchange Format File

CAD Files

7Z file extension

7-Zip Compressed File

Compressed Files

CPL file extension

Windows Control Panel Item

System Files