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Favicon


A favicon (short for "Favorites icon"), also known as a page icon, is an icon associated with a particular website or web page. A web designer can create such an icon, and many graphical web browsers—such as recent versions of Internet Explorer, Firefox, Mozilla, Opera, Safari, and Konqueror—can then make use of them. Browsers that support favicons may 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 the link element like: <link rel="shortcut icon" href="favicon.ico"> in the <head> section of the document. In this way, any appropriately sized (16×16 pixels or larger) 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 requests for the file "favicon.ico" even if it doesn't exist. Another common problem is that the favicons may disappear if the browser's cache is emptied.

Standardization

The favicon file format (.ico) was originally created by Microsoft, and Microsoft's Internet Explorer web browser would request a favicon from a conventional website URL (/favicon.ico) on every website. Microsoft's supported format for the link tag did not conform to the World Wide Web Consortium (W3C) HTML recommendation because:

  • The rel attribute must contain a space-delimited list of link types, so a two-word link type would not be understood correctly by conforming web browsers.
  • The ".ico" file format was not a standard MIME type, and wasn't likely to be automatically understood by most web browsers.

The Mozilla web browser added support for favicons, including a version that conformed to web standards: The use of rel="icon" and optional mime-type (e.g., image/png) let web designers add favicons while conforming to W3C standards. Many web browsers have since added support for this feature. 

<link rel="icon" type="image/png" href="/path/image.png">

In 2003 Microsoft's .ico format was registered with the Internet Assigned Numbers Authority (IANA) under the MIME type image/vnd.microsoft.icon.

Related concepts

  • Favatars are the application of favicons as weblog avatars.
  • Gravatars (Globally Recognized Avatars) are centralized square images representing commenters in weblogs.
  • NotesBuddy is an experimental Lotus Notes application putting sender faces in email, among many other things
  • Picons (Personal Icons) are icons representing email addresses and server names.
  • Vismon was the Bell Labs system which put faces in email and inspired Picons
  • X-Face is a standard mail header for sending 48 by 48 pixel images of senders

External links

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07-14-2008 23:18:10
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