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

BAK file extension

Backup File

Backup Files

CFG file extension

Configuration File

Settings Files

CRX file extension

Chrome Extension

Plugin Files

DEM file extension

Video Game Demo File

Game Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

ICO file extension

Icon File

System Files

IFF file extension

Interchange File Format

Audio Files

M file extension

Objective-C Implementation File

Developer Files

PART file extension

Partially Downloaded File

Misc Files

PHP file extension

PHP Source Code File

Web Files

PNG file extension

Portable Network Graphic

Raster Image Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

SYS file extension

Windows System File

System Files

WAV file extension

WAVE Audio File

Audio Files