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

ASP file extension

Active Server Page

Web Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

FLA file extension

Adobe Flash Animation

Developer Files

IBOOKS file extension

Multi-Touch iBook

Data Files

ICO file extension

Icon File

System Files

INDD file extension

Adobe InDesign Document

Layout Files

ISO file extension

Disc Image File

Disk Image Files

KEY file extension

Keynote Presentation

Data Files

M file extension

Objective-C Implementation File

Developer Files

MSI file extension

Windows Installer Package

Misc Files

PAGES file extension

Pages Document

Text Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

RM file extension

Real Media File

Video Files

WMV file extension

Windows Media Video File

Video Files