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

AVI file extension

Audio Video Interleave File

Video Files

BAK file extension

Backup File

Backup Files

CRX file extension

Chrome Extension

Plugin Files

CS file extension

Visual C# Source Code File

Developer Files

FON file extension

Generic Font File

Font Files

GAM file extension

Saved Game File

Game Files

ICS file extension

iCalendar File

Misc Files

PDF file extension

Portable Document Format File

Layout Files

PNG file extension

Portable Network Graphic

Raster Image Files

RSS file extension

Rich Site Summary

Web Files

SYS file extension

Windows System File

System Files

TOAST file extension

Toast Disc Image

Disk Image Files

TORRENT file extension

BitTorrent File

Misc Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files