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

ASF file extension

Advanced Systems Format File

Video Files

CAB file extension

Windows Cabinet File

System Files

DOC# file extension

Microsoft Word Document

Text Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

H file extension

C/C++/Objective-C Header File

Developer Files

ICO file extension

Icon File

System Files

KML file extension

Keyhole Markup Language File

GIS Files

MSI file extension

Windows Installer Package

Misc Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PS file extension

PostScript File

Vector Image Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

SRT file extension

SubRip Subtitle File

Video Files

SWF file extension

Shockwave Flash Movie

Video Files

VCF file extension

vCard File

Data Files

3GP file extension

3GPP Multimedia File

Video Files