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

ASX file extension

Microsoft ASF Redirector File

Video Files

AZW file extension

Amazon Kindle eBook File

eBook Files

C file extension

C/C++ Source Code File

Developer Files

CLASS file extension

Java Class File

Developer Files

CPL file extension

Windows Control Panel Item

System Files

DAT file extension

Data File

Data Files

DBF file extension

Database File

Database Files

DOC# file extension

Microsoft Word Document

Text Files

KML file extension

Keyhole Markup Language File

GIS Files

LNK file extension

Windows File Shortcut

System Files

M4A file extension

MPEG-4 Audio File

Audio Files

PART file extension

Partially Downloaded File

Misc Files

PPS file extension

PowerPoint Slide Show

Data Files

RM file extension

Real Media File

Video Files

TOAST file extension

Toast Disc Image

Disk Image Files