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

CFG file extension

Configuration File

Settings Files

COM file extension

DOS Command File

Executable Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DXF file extension

Drawing Exchange Format File

CAD Files

EXE file extension

Windows Executable File

Executable Files

GPX file extension

GPS Exchange File

GIS Files

ICS file extension

iCalendar File

Misc Files

KML file extension

Keyhole Markup Language File

GIS Files

MSG file extension

Outlook Mail Message

Text Files

ODT file extension

OpenDocument Text Document

Text Files

PPS file extension

PowerPoint Slide Show

Data Files

RM file extension

Real Media File

Video Files

XLR file extension

Works Spreadsheet

Spreadsheet Files