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

7Z file extension

7-Zip Compressed File

Compressed Files

TXT file extension

Plain Text File

Text Files

JPG file extension

JPEG Image

Raster Image Files

APP file extension

Mac OS X Application

Executable Files

SAV file extension

Saved Game

Game Files

PCT file extension

Picture File

Layout Files

MPG file extension

MPEG Video File

Video Files

ICO file extension

Icon File

System Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

CRX file extension

Chrome Extension

Plugin Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

PPS file extension

PowerPoint Slide Show

Data Files

C file extension

C/C++ Source Code File

Developer Files

SQL file extension

Structured Query Language Data File

Database Files