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

CPP file extension

C++ Source Code File

Developer Files

CRX file extension

Chrome Extension

Plugin Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

GADGET file extension

Windows Gadget

Executable Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

JAR file extension

Java Archive File

Executable Files

MOV file extension

Apple QuickTime Movie

Video Files

PART file extension

Partially Downloaded File

Misc Files

PKG file extension

Mac OS X Installer Package

Compressed Files

SQL file extension

Structured Query Language Data File

Database Files

TORRENT file extension

BitTorrent File

Misc Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

YUV file extension

YUV Encoded Image File

Raster Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files