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

M file extension

Objective-C Implementation File

Developer Files

SWF file extension

Shockwave Flash Movie

Video Files

ROM file extension

N64 Game ROM File

Game Files

TXT file extension

Plain Text File

Text Files

PCT file extension

Picture File

Layout Files

CAB file extension

Windows Cabinet File

System Files

MSI file extension

Windows Installer Package

Misc Files

GAM file extension

Saved Game File

Game Files

IBOOKS file extension

Multi-Touch iBook

Data Files

7Z file extension

7-Zip Compressed File

Compressed Files

DNG file extension

Digital Negative Image File

Camera Raw Files

3DM file extension

Rhino 3D Model

3D Image Files

PL file extension

Perl Script

Developer Files

DXF file extension

Drawing Exchange Format File

CAD Files

GPX file extension

GPS Exchange File

GIS Files