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

ASX file extension

Microsoft ASF Redirector File

Video Files

AZW file extension

Amazon Kindle eBook File

eBook Files

CPL file extension

Windows Control Panel Item

System Files

DOC# file extension

Microsoft Word Document

Text Files

FNT file extension

Windows Font File

Font Files

GADGET file extension

Windows Gadget

Executable Files

GZ file extension

Gnu Zipped Archive

Compressed Files

ICO file extension

Icon File

System Files

MPG file extension

MPEG Video File

Video Files

PAGES file extension

Pages Document

Text Files

PCT file extension

Picture File

Layout Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SITX file extension

StuffIt X Archive

Compressed Files

SLN file extension

Visual Studio Solution File

Developer Files