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

ASX file extension

Microsoft ASF Redirector File

Video Files

CFM file extension

ColdFusion Markup File

Web Files

DDS file extension

DirectDraw Surface

Raster Image Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

HTML file extension

Hypertext Markup Language File

Web Files

IFF file extension

Interchange File Format

Audio Files

JPG file extension

JPEG Image

Raster Image Files

KEY file extension

Keynote Presentation

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

MOV file extension

Apple QuickTime Movie

Video Files

PY file extension

Python Script

Developer Files

SWF file extension

Shockwave Flash Movie

Video Files

TEX file extension

LaTeX Source Document

Text Files