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

EPUB file extension

Open eBook File

eBook Files

FON file extension

Generic Font File

Font Files

IBOOKS file extension

Multi-Touch iBook

Data Files

KEY file extension

Keynote Presentation

Data Files

M file extension

Objective-C Implementation File

Developer Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PRF file extension

Outlook Profile File

Settings Files

SAV file extension

Saved Game

Game Files

SWF file extension

Shockwave Flash Movie

Video Files

TAR file extension

Consolidated Unix File Archive

Data Files

TIF file extension

Tagged Image File

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

XCODEPROJ file extension

Xcode Project

Developer Files

XLR file extension

Works Spreadsheet

Spreadsheet Files