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

APP file extension

Mac OS X Application

Executable Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

GADGET file extension

Windows Gadget

Executable Files

GAM file extension

Saved Game File

Game Files

HTM file extension

Hypertext Markup Language File

Web Files

ICO file extension

Icon File

System Files

INI file extension

Windows Initialization File

Settings Files

JAVA file extension

Java Source Code File

Developer Files

JSP file extension

Java Server Page

Web Files

LUA file extension

Lua Source File

Developer Files

PIF file extension

Program Information File

Executable Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PNG file extension

Portable Network Graphic

Raster Image Files

WMV file extension

Windows Media Video File

Video Files

WPS file extension

Microsoft Works Word Processor Document

Text Files