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

CFM file extension

ColdFusion Markup File

Web Files

CSS file extension

Cascading Style Sheet

Web Files

EPUB file extension

Open eBook File

eBook Files

GED file extension

GEDCOM Genealogy Data File

Data Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

JAVA file extension

Java Source Code File

Developer Files

JPG file extension

JPEG Image

Raster Image Files

KMZ file extension

Google Earth Placemark File

GIS Files

MID file extension

MIDI File

Audio Files

MOV file extension

Apple QuickTime Movie

Video Files

PL file extension

Perl Script

Developer Files

PPT file extension

PowerPoint Presentation

Data Files

SITX file extension

StuffIt X Archive

Compressed Files

XML file extension

XML File

Data Files

ZIP file extension

Zipped File

Compressed Files