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

SVG file extension

Scalable Vector Graphics File

Vector Image Files

THM file extension

Thumbnail Image File

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

HTML file extension

Hypertext Markup Language File

Web Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

JS file extension

JavaScript File

Web Files

CLASS file extension

Java Class File

Developer Files

KMZ file extension

Google Earth Placemark File

GIS Files

MOV file extension

Apple QuickTime Movie

Video Files

ASPX file extension

Active Server Page Extended File

Web Files

RSS file extension

Rich Site Summary

Web Files

GED file extension

GEDCOM Genealogy Data File

Data Files

VCF file extension

vCard File

Data Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

PHP file extension

PHP Source Code File

Web Files