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

DB file extension

Database File

Database Files

DDS file extension

DirectDraw Surface

Raster Image Files

DNG file extension

Digital Negative Image File

Camera Raw Files

JAVA file extension

Java Source Code File

Developer Files

KML file extension

Keyhole Markup Language File

GIS Files

M file extension

Objective-C Implementation File

Developer Files

MID file extension

MIDI File

Audio Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PNG file extension

Portable Network Graphic

Raster Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

WSF file extension

Windows Script File

Executable Files

XML file extension

XML File

Data Files

3GP file extension

3GPP Multimedia File

Video Files