A typical 16×16 pixel favicon
A favicon, also known as a page icon, is an icon associated with a particular website. A web designer can create such an icon, and many graphical web browsers – such as recent versions of Internet Explorer, Mozilla, Opera, and Konqueror – can then make use of them. Browsers that support favicons display them in the browser’s address bar, next to the site’s name in lists of bookmarks, and next to the page’s title in a Tabbed Document Interface.
The original means of defining a favicon was by placing a file called favicon.ico in the root directory of a webserver. This would then automatically be used in Internet Explorer’s favorites (bookmarks) display. Later, however, a more flexible system was created, using HTML to indicate the location of an icon for any given page. This is achieved using a tag of the form <link rel=”shortcut icon” href=”favicon.ico”> in the <head> section of the page. In this way, any appropriately sized image can be used, and although many still use the .ico format, others use GIF or PNG files.
Most modern browsers implement both methods. Because of this, web servers receive many request for the file “favicon.ico” even if it doesn’t exist, causing irritation for administrators looking through their log files.