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

AZW file extension

Amazon Kindle eBook File

eBook Files

TAR file extension

Consolidated Unix File Archive

Data Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

DTD file extension

Document Type Definition File

Developer Files

ACCDB file extension

Access 2007 Database File

Database Files

APK file extension

Android Package File

Executable Files

MOV file extension

Apple QuickTime Movie

Video Files

3DM file extension

Rhino 3D Model

3D Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

SYS file extension

Windows System File

System Files

CPP file extension

C++ Source Code File

Developer Files

CSS file extension

Cascading Style Sheet

Web Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

ROM file extension

N64 Game ROM File

Game Files

GIF file extension

Graphical Interchange Format File

Raster Image Files