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

BIN file extension

Binary Disc Image

Disk Image Files

CSS file extension

Cascading Style Sheet

Web Files

DB file extension

Database File

Database Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

GADGET file extension

Windows Gadget

Executable Files

GPX file extension

GPS Exchange File

GIS Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

JS file extension

JavaScript File

Web Files

KML file extension

Keyhole Markup Language File

GIS Files

LUA file extension

Lua Source File

Developer Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

SDF file extension

Standard Data File

Data Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

YUV file extension

YUV Encoded Image File

Raster Image Files