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

DEB file extension

Debian Software Package

Compressed Files

WMV file extension

Windows Media Video File

Video Files

INDD file extension

Adobe InDesign Document

Layout Files

IFF file extension

Interchange File Format

Audio Files

PL file extension

Perl Script

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

TTF file extension

TrueType Font

Font Files

SLN file extension

Visual Studio Solution File

Developer Files

PNG file extension

Portable Network Graphic

Raster Image Files

CAB file extension

Windows Cabinet File

System Files

TIF file extension

Tagged Image File

Raster Image Files

JPG file extension

JPEG Image

Raster Image Files

VCD file extension

Virtual CD

Disk Image Files

INI file extension

Windows Initialization File

Settings Files

KML file extension

Keyhole Markup Language File

GIS Files