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

ACCDB file extension

Access 2007 Database File

Database Files

ASF file extension

Advanced Systems Format File

Video Files

ASX file extension

Microsoft ASF Redirector File

Video Files

DAT file extension

Data File

Data Files

DDS file extension

DirectDraw Surface

Raster Image Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

DXF file extension

Drawing Exchange Format File

CAD Files

FON file extension

Generic Font File

Font Files

GBR file extension

Gerber File

Data Files

ISO file extension

Disc Image File

Disk Image Files

LOG file extension

Log File

Text Files

M4V file extension

iTunes Video File

Video Files

MPG file extension

MPEG Video File

Video Files

PPT file extension

PowerPoint Presentation

Data Files

RAR file extension

WinRAR Compressed Archive

Compressed Files