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

BAT file extension

DOS Batch File

Executable Files

CFG file extension

Configuration File

Settings Files

CPP file extension

C++ Source Code File

Developer Files

GED file extension

GEDCOM Genealogy Data File

Data Files

HTM file extension

Hypertext Markup Language File

Web Files

KML file extension

Keyhole Markup Language File

GIS Files

MPG file extension

MPEG Video File

Video Files

PPT file extension

PowerPoint Presentation

Data Files

PRF file extension

Outlook Profile File

Settings Files

SITX file extension

StuffIt X Archive

Compressed Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

WAV file extension

WAVE Audio File

Audio Files

WMV file extension

Windows Media Video File

Video Files

XCODEPROJ file extension

Xcode Project

Developer Files

XLR file extension

Works Spreadsheet

Spreadsheet Files