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

CSS file extension

Cascading Style Sheet

Web Files

DAT file extension

Data File

Data Files

DDS file extension

DirectDraw Surface

Raster Image Files

DLL file extension

Dynamic Link Library

System Files

DRV file extension

Device Driver

System Files

GPX file extension

GPS Exchange File

GIS Files

IFF file extension

Interchange File Format

Audio Files

ISO file extension

Disc Image File

Disk Image Files

JPG file extension

JPEG Image

Raster Image Files

PS file extension

PostScript File

Vector Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

RSS file extension

Rich Site Summary

Web Files

VCXPROJ file extension

Visual C++ Project

Developer Files

WPD file extension

WordPerfect Document

Text Files