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

AVI file extension

Audio Video Interleave File

Video Files

AZW file extension

Amazon Kindle eBook File

eBook Files

BAK file extension

Backup File

Backup Files

C file extension

C/C++ Source Code File

Developer Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

FLA file extension

Adobe Flash Animation

Developer Files

FON file extension

Generic Font File

Font Files

IBOOKS file extension

Multi-Touch iBook

Data Files

JPG file extension

JPEG Image

Raster Image Files

JS file extension

JavaScript File

Web Files

MP4 file extension

MPEG-4 Video File

Video Files

NES file extension

Nintendo (NES) ROM File

Game Files

PRF file extension

Outlook Profile File

Settings Files

VOB file extension

DVD Video Object File

Video Files

ZIPX file extension

Extended Zip File

Compressed Files