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

CGI file extension

Common Gateway Interface Script

Executable Files

CRX file extension

Chrome Extension

Plugin Files

CSV file extension

Comma Separated Values File

Data Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

GED file extension

GEDCOM Genealogy Data File

Data Files

HTML file extension

Hypertext Markup Language File

Web Files

IFF file extension

Interchange File Format

Audio Files

KMZ file extension

Google Earth Placemark File

GIS Files

MSI file extension

Windows Installer Package

Misc Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PPT file extension

PowerPoint Presentation

Data Files

TARGZ file extension

Compressed Tarball File

Compressed Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

WSF file extension

Windows Script File

Executable Files