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

BIN file extension

Binary Disc Image

Disk Image Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

DXF file extension

Drawing Exchange Format File

CAD Files

GAM file extension

Saved Game File

Game Files

HTML file extension

Hypertext Markup Language File

Web Files

MDB file extension

Microsoft Access Database

Database Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MPA file extension

MPEG-2 Audio File

Audio Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PRF file extension

Outlook Profile File

Settings Files

SYS file extension

Windows System File

System Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TEX file extension

LaTeX Source Document

Text Files

3G2 file extension

3GPP2 Multimedia File

Video Files