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

APP file extension

Mac OS X Application

Executable Files

ASP file extension

Active Server Page

Web Files

CRX file extension

Chrome Extension

Plugin Files

CSS file extension

Cascading Style Sheet

Web Files

DRV file extension

Device Driver

System Files

EXE file extension

Windows Executable File

Executable Files

GAM file extension

Saved Game File

Game Files

INI file extension

Windows Initialization File

Settings Files

JAR file extension

Java Archive File

Executable Files

MP3 file extension

MP3 Audio File

Audio Files

PL file extension

Perl Script

Developer Files

PY file extension

Python Script

Developer Files

RM file extension

Real Media File

Video Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TIF file extension

Tagged Image File

Raster Image Files