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

BAT file extension

DOS Batch File

Executable Files

DEB file extension

Debian Software Package

Compressed Files

DTD file extension

Document Type Definition File

Developer Files

EPUB file extension

Open eBook File

eBook Files

FON file extension

Generic Font File

Font Files

H file extension

C/C++/Objective-C Header File

Developer Files

INDD file extension

Adobe InDesign Document

Layout Files

MSI file extension

Windows Installer Package

Misc Files

PCT file extension

Picture File

Layout Files

PIF file extension

Program Information File

Executable Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PNG file extension

Portable Network Graphic

Raster Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SAV file extension

Saved Game

Game Files

VCF file extension

vCard File

Data Files