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

CSS file extension

Cascading Style Sheet

Web Files

PRF file extension

Outlook Profile File

Settings Files

PL file extension

Perl Script

Developer Files

VCF file extension

vCard File

Data Files

MPG file extension

MPEG Video File

Video Files

AZW file extension

Amazon Kindle eBook File

eBook Files

7Z file extension

7-Zip Compressed File

Compressed Files

AIF file extension

Audio Interchange File Format

Audio Files

DOC file extension

Microsoft Word Document

Text Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

MSG file extension

Outlook Mail Message

Text Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

CAB file extension

Windows Cabinet File

System Files

GED file extension

GEDCOM Genealogy Data File

Data Files

GAM file extension

Saved Game File

Game Files