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

AIF file extension

Audio Interchange File Format

Audio Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

HTML file extension

Hypertext Markup Language File

Web Files

IFF file extension

Interchange File Format

Audio Files

JPG file extension

JPEG Image

Raster Image Files

JS file extension

JavaScript File

Web Files

KEY file extension

Keynote Presentation

Data Files

PDF file extension

Portable Document Format File

Layout Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PNG file extension

Portable Network Graphic

Raster Image Files

PPS file extension

PowerPoint Slide Show

Data Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

TAR file extension

Consolidated Unix File Archive

Data Files

WPS file extension

Microsoft Works Word Processor Document

Text Files