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

CRX file extension

Chrome Extension

Plugin Files

DAT file extension

Data File

Data Files

DB file extension

Database File

Database Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

EPUB file extension

Open eBook File

eBook Files

FNT file extension

Windows Font File

Font Files

IBOOKS file extension

Multi-Touch iBook

Data Files

MOV file extension

Apple QuickTime Movie

Video Files

PAGES file extension

Pages Document

Text Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

SWF file extension

Shockwave Flash Movie

Video Files

TAR file extension

Consolidated Unix File Archive

Data Files

THM file extension

Thumbnail Image File

Raster Image Files

XML file extension

XML File

Data Files

3DM file extension

Rhino 3D Model

3D Image Files