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

APK file extension

Android Package File

Executable Files

C file extension

C/C++ Source Code File

Developer Files

DEM file extension

Video Game Demo File

Game Files

FNT file extension

Windows Font File

Font Files

ICS file extension

iCalendar File

Misc Files

ISO file extension

Disc Image File

Disk Image Files

JS file extension

JavaScript File

Web Files

KML file extension

Keyhole Markup Language File

GIS Files

LOG file extension

Log File

Text Files

MOV file extension

Apple QuickTime Movie

Video Files

OTF file extension

OpenType Font

Font Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XML file extension

XML File

Data Files