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

JAR file extension

Java Archive File

Executable Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PDB file extension

Program Database

Database Files

LUA file extension

Lua Source File

Developer Files

DOC# file extension

Microsoft Word Document

Text Files

ZIPX file extension

Extended Zip File

Compressed Files

CSS file extension

Cascading Style Sheet

Web Files

PIF file extension

Program Information File

Executable Files

SYS file extension

Windows System File

System Files

7Z file extension

7-Zip Compressed File

Compressed Files

ZIP file extension

Zipped File

Compressed Files

ROM file extension

N64 Game ROM File

Game Files

MOBI file extension

Mobipocket eBook

eBook Files