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

DDS file extension

DirectDraw Surface

Raster Image Files

VOB file extension

DVD Video Object File

Video Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

AI file extension

Adobe Illustrator File

Vector Image Files

PCT file extension

Picture File

Layout Files

DOC# file extension

Microsoft Word Document

Text Files

H file extension

C/C++/Objective-C Header File

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

JSP file extension

Java Server Page

Web Files

WPD file extension

WordPerfect Document

Text Files

PHP file extension

PHP Source Code File

Web Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

KML file extension

Keyhole Markup Language File

GIS Files

FON file extension

Generic Font File

Font Files

OTF file extension

OpenType Font

Font Files