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

CRX file extension

Chrome Extension

Plugin Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GBR file extension

Gerber File

Data Files

HTML file extension

Hypertext Markup Language File

Web Files

IBOOKS file extension

Multi-Touch iBook

Data Files

JSP file extension

Java Server Page

Web Files

M3U file extension

Media Playlist File

Audio Files

MDF file extension

Media Disc Image File

Disk Image Files

MPA file extension

MPEG-2 Audio File

Audio Files

PDF file extension

Portable Document Format File

Layout Files

PPT file extension

PowerPoint Presentation

Data Files

RSS file extension

Rich Site Summary

Web Files

TAR file extension

Consolidated Unix File Archive

Data Files

TTF file extension

TrueType Font

Font Files