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

AIF file extension

Audio Interchange File Format

Audio Files

ASP file extension

Active Server Page

Web Files

BAT file extension

DOS Batch File

Executable Files

CSS file extension

Cascading Style Sheet

Web Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

FNT file extension

Windows Font File

Font Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

INI file extension

Windows Initialization File

Settings Files

KML file extension

Keyhole Markup Language File

GIS Files

PART file extension

Partially Downloaded File

Misc Files

PHP file extension

PHP Source Code File

Web Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

SQL file extension

Structured Query Language Data File

Database Files

TEX file extension

LaTeX Source Document

Text Files

VCD file extension

Virtual CD

Disk Image Files