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

ASPX file extension

Active Server Page Extended File

Web Files

CER file extension

Internet Security Certificate

Web Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

FON file extension

Generic Font File

Font Files

GED file extension

GEDCOM Genealogy Data File

Data Files

ICO file extension

Icon File

System Files

ISO file extension

Disc Image File

Disk Image Files

KMZ file extension

Google Earth Placemark File

GIS Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PS file extension

PostScript File

Vector Image Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

SH file extension

Bash Shell Script

Developer Files

WSF file extension

Windows Script File

Executable Files

XML file extension

XML File

Data Files

3DS file extension

3D Studio Scene

3D Image Files