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

ASX file extension

Microsoft ASF Redirector File

Video Files

CGI file extension

Common Gateway Interface Script

Executable Files

CLASS file extension

Java Class File

Developer Files

DEB file extension

Debian Software Package

Compressed Files

GBR file extension

Gerber File

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

ISO file extension

Disc Image File

Disk Image Files

LNK file extension

Windows File Shortcut

System Files

M file extension

Objective-C Implementation File

Developer Files

NES file extension

Nintendo (NES) ROM File

Game Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PNG file extension

Portable Network Graphic

Raster Image Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SWF file extension

Shockwave Flash Movie

Video Files

TGA file extension

Targa Graphic

Raster Image Files