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

AI file extension

Adobe Illustrator File

Vector Image Files

AZW file extension

Amazon Kindle eBook File

eBook Files

C file extension

C/C++ Source Code File

Developer Files

CGI file extension

Common Gateway Interface Script

Executable Files

DMP file extension

Windows Memory Dump

System Files

DOC# file extension

Microsoft Word Document

Text Files

FLA file extension

Adobe Flash Animation

Developer Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

LNK file extension

Windows File Shortcut

System Files

M4V file extension

iTunes Video File

Video Files

MOV file extension

Apple QuickTime Movie

Video Files

PCT file extension

Picture File

Layout Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PNG file extension

Portable Network Graphic

Raster Image Files

UUE file extension

Uuencoded File

Encoded Files