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

BAK file extension

Backup File

Backup Files

CRX file extension

Chrome Extension

Plugin Files

CSR file extension

Certificate Signing Request File

Web Files

GED file extension

GEDCOM Genealogy Data File

Data Files

INI file extension

Windows Initialization File

Settings Files

M3U file extension

Media Playlist File

Audio Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PL file extension

Perl Script

Developer Files

PNG file extension

Portable Network Graphic

Raster Image Files

RA file extension

Real Audio File

Audio Files

RSS file extension

Rich Site Summary

Web Files

SRT file extension

SubRip Subtitle File

Video Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

THM file extension

Thumbnail Image File

Raster Image Files