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

DB file extension

Database File

Database Files

LUA file extension

Lua Source File

Developer Files

PDB file extension

Program Database

Database Files

PHP file extension

PHP Source Code File

Web Files

SITX file extension

StuffIt X Archive

Compressed Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TORRENT file extension

BitTorrent File

Misc Files

WMV file extension

Windows Media Video File

Video Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

YUV file extension

YUV Encoded Image File

Raster Image Files

3DS file extension

3D Studio Scene

3D Image Files