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

CLASS file extension

Java Class File

Developer Files

CUR file extension

Windows Cursor

System Files

DDS file extension

DirectDraw Surface

Raster Image Files

DRV file extension

Device Driver

System Files

FLA file extension

Adobe Flash Animation

Developer Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

INDD file extension

Adobe InDesign Document

Layout Files

INI file extension

Windows Initialization File

Settings Files

JAVA file extension

Java Source Code File

Developer Files

MDB file extension

Microsoft Access Database

Database Files

SAV file extension

Saved Game

Game Files

SWF file extension

Shockwave Flash Movie

Video Files

VB file extension

VBScript File

Executable Files

VOB file extension

DVD Video Object File

Video Files

3GP file extension

3GPP Multimedia File

Video Files