ICO

ICO file format is an image file format for icons in Microsoft Windows. ICO files contain one or more small images at multiple sizes and color depths. The official IANA-registered MIME type for ICO files is. Erroneous labels “ ”, “ ”, “ ” and “ ”, along with the unofficial name “ ” were in use at the time of official registration and assignment of the MIME type. ICO files usually come in the size of 16x16px or 32x32px, but there are also icons that are 48x48px or 128x128px in size. Some icons have all the sizes combined into one file for compatibility.

In web design, ICO images are used as the website's favicon. Authors would then link the favicon to their web page using the HTML  element.

The file extension is.