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

ASP file extension

Active Server Page

Web Files

ASX file extension

Microsoft ASF Redirector File

Video Files

AVI file extension

Audio Video Interleave File

Video Files

CFM file extension

ColdFusion Markup File

Web Files

CRX file extension

Chrome Extension

Plugin Files

CSR file extension

Certificate Signing Request File

Web Files

DLL file extension

Dynamic Link Library

System Files

DRV file extension

Device Driver

System Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

FON file extension

Generic Font File

Font Files

GADGET file extension

Windows Gadget

Executable Files

MID file extension

MIDI File

Audio Files

SLN file extension

Visual Studio Solution File

Developer Files

VOB file extension

DVD Video Object File

Video Files

XML file extension

XML File

Data Files