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

CFM file extension

ColdFusion Markup File

Web Files

CGI file extension

Common Gateway Interface Script

Executable Files

EXE file extension

Windows Executable File

Executable Files

FLA file extension

Adobe Flash Animation

Developer Files

GAM file extension

Saved Game File

Game Files

JSP file extension

Java Server Page

Web Files

LUA file extension

Lua Source File

Developer Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

ROM file extension

N64 Game ROM File

Game Files

RPM file extension

Red Hat Package Manager File

Compressed Files

TOAST file extension

Toast Disc Image

Disk Image Files

XCODEPROJ file extension

Xcode Project

Developer Files

XML file extension

XML File

Data Files

ZIPX file extension

Extended Zip File

Compressed Files