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

CLASS file extension

Java Class File

Developer Files

DB file extension

Database File

Database Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

GED file extension

GEDCOM Genealogy Data File

Data Files

JS file extension

JavaScript File

Web Files

KMZ file extension

Google Earth Placemark File

GIS Files

MPG file extension

MPEG Video File

Video Files

MSI file extension

Windows Installer Package

Misc Files

PCT file extension

Picture File

Layout Files

PHP file extension

PHP Source Code File

Web Files

TAR file extension

Consolidated Unix File Archive

Data Files

TIFF file extension

Tagged Image File Format

Raster Image Files

TXT file extension

Plain Text File

Text Files

ZIPX file extension

Extended Zip File

Compressed Files