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

APK file extension

Android Package File

Executable Files

BAT file extension

DOS Batch File

Executable Files

C file extension

C/C++ Source Code File

Developer 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

MAX file extension

3ds Max Scene File

3D Image Files

MID file extension

MIDI File

Audio Files

ODT file extension

OpenDocument Text Document

Text Files

PKG file extension

Mac OS X Installer Package

Compressed Files

XCODEPROJ file extension

Xcode Project

Developer Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XML file extension

XML File

Data Files

ZIPX file extension

Extended Zip File

Compressed Files

3DM file extension

Rhino 3D Model

3D Image Files