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

PPT file extension

PowerPoint Presentation

Data Files

DAT file extension

Data File

Data Files

INDD file extension

Adobe InDesign Document

Layout Files

CFG file extension

Configuration File

Settings Files

7Z file extension

7-Zip Compressed File

Compressed Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

DDS file extension

DirectDraw Surface

Raster Image Files

WMV file extension

Windows Media Video File

Video Files

SRT file extension

SubRip Subtitle File

Video Files

JAVA file extension

Java Source Code File

Developer Files

SAV file extension

Saved Game

Game Files

XCODEPROJ file extension

Xcode Project

Developer Files

FLA file extension

Adobe Flash Animation

Developer Files

VOB file extension

DVD Video Object File

Video Files

TMP file extension

Temporary File

Backup Files