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

CPL file extension

Windows Control Panel Item

System Files

CSS file extension

Cascading Style Sheet

Web Files

DDS file extension

DirectDraw Surface

Raster Image Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

FON file extension

Generic Font File

Font Files

GBR file extension

Gerber File

Data Files

GED file extension

GEDCOM Genealogy Data File

Data Files

INI file extension

Windows Initialization File

Settings Files

ISO file extension

Disc Image File

Disk Image Files

PKG file extension

Mac OS X Installer Package

Compressed Files

RM file extension

Real Media File

Video Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

TGA file extension

Targa Graphic

Raster Image Files

WAV file extension

WAVE Audio File

Audio Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files