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

ASPX file extension

Active Server Page Extended File

Web Files

CAB file extension

Windows Cabinet File

System Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

DNG file extension

Digital Negative Image File

Camera Raw Files

EXE file extension

Windows Executable File

Executable Files

LNK file extension

Windows File Shortcut

System Files

LOG file extension

Log File

Text Files

LUA file extension

Lua Source File

Developer Files

MP3 file extension

MP3 Audio File

Audio Files

MSI file extension

Windows Installer Package

Misc Files

ODT file extension

OpenDocument Text Document

Text Files

PART file extension

Partially Downloaded File

Misc Files

PIF file extension

Program Information File

Executable Files

TIFF file extension

Tagged Image File Format

Raster Image Files

XCODEPROJ file extension

Xcode Project

Developer Files