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

DDS file extension

DirectDraw Surface

Raster Image Files

DLL file extension

Dynamic Link Library

System Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GADGET file extension

Windows Gadget

Executable Files

INDD file extension

Adobe InDesign Document

Layout Files

JPG file extension

JPEG Image

Raster Image Files

LUA file extension

Lua Source File

Developer Files

PCT file extension

Picture File

Layout Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SLN file extension

Visual Studio Solution File

Developer Files

TORRENT file extension

BitTorrent File

Misc Files

WSF file extension

Windows Script File

Executable Files

ZIP file extension

Zipped File

Compressed Files

3DM file extension

Rhino 3D Model

3D Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files