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

CS file extension

Visual C# Source Code File

Developer Files

DDS file extension

DirectDraw Surface

Raster Image Files

TIF file extension

Tagged Image File

Raster Image Files

MOV file extension

Apple QuickTime Movie

Video Files

JSP file extension

Java Server Page

Web Files

CRX file extension

Chrome Extension

Plugin Files

ASX file extension

Microsoft ASF Redirector File

Video Files

GBR file extension

Gerber File

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

APP file extension

Mac OS X Application

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

BAT file extension

DOS Batch File

Executable Files

COM file extension

DOS Command File

Executable Files

RSS file extension

Rich Site Summary

Web Files

WPS file extension

Microsoft Works Word Processor Document

Text Files