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

7Z file extension

7-Zip Compressed File

Compressed Files

DLL file extension

Dynamic Link Library

System Files

JS file extension

JavaScript File

Web Files

ZIPX file extension

Extended Zip File

Compressed Files

LUA file extension

Lua Source File

Developer Files

3DM file extension

Rhino 3D Model

3D Image Files

ICS file extension

iCalendar File

Misc Files

INI file extension

Windows Initialization File

Settings Files

DB file extension

Database File

Database Files

ASP file extension

Active Server Page

Web Files

APP file extension

Mac OS X Application

Executable Files

CUE file extension

Cue Sheet File

Disk Image Files

M4V file extension

iTunes Video File

Video Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

TARGZ file extension

Compressed Tarball File

Compressed Files