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

ACCDB file extension

Access 2007 Database File

Database Files

CRX file extension

Chrome Extension

Plugin Files

DAT file extension

Data File

Data Files

DEB file extension

Debian Software Package

Compressed Files

FLV file extension

Flash Video File

Video Files

FON file extension

Generic Font File

Font Files

IFF file extension

Interchange File Format

Audio Files

INDD file extension

Adobe InDesign Document

Layout Files

KEY file extension

Keynote Presentation

Data Files

KMZ file extension

Google Earth Placemark File

GIS Files

LOG file extension

Log File

Text Files

LUA file extension

Lua Source File

Developer Files

MOV file extension

Apple QuickTime Movie

Video Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

XCODEPROJ file extension

Xcode Project

Developer Files