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

AI file extension

Adobe Illustrator File

Vector Image Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

GADGET file extension

Windows Gadget

Executable Files

GED file extension

GEDCOM Genealogy Data File

Data Files

INI file extension

Windows Initialization File

Settings Files

M4A file extension

MPEG-4 Audio File

Audio Files

MOBI file extension

Mobipocket eBook

eBook Files

MSG file extension

Outlook Mail Message

Text Files

PCT file extension

Picture File

Layout Files

RSS file extension

Rich Site Summary

Web Files

SH file extension

Bash Shell Script

Developer Files

TARGZ file extension

Compressed Tarball File

Compressed Files

VB file extension

VBScript File

Executable Files

WPD file extension

WordPerfect Document

Text Files

XML file extension

XML File

Data Files