Favicon

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Favicons are displayed in all major graphical browsers.

A favicon (short for favorites icon), also known as a website icon, shortcut icon, url icon, or bookmark icon is an icon associated with a particular website or webpage. A web designer can create such an icon and install it into a website (or webpage) by several means, and most graphical web browsers will then make use of it. Browsers that provide favicon support typically display a page's favicon in the browser's URL bar and next to the page's name in a list of bookmarks. Browsers that support a tabbed document interface typically show a page's favicon next to the page's title. The Microsoft Windows Shell uses favicons to represent "Internet shortcuts" to web pages.

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[edit] Use

The original means of defining a favicon was by placing a file called favicon.ico in the root directory of a web server. 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 by adding a link element to the <head> section of the document as detailed below. In this way any appropriately sized (16×16 pixels or larger) image can be used and, although many still use the ICO format, other browsers (though not Microsoft's Internet Explorer) now also support the PNG and animated GIF image formats.

However, Microsoft Internet Explorer only truly supports icons that have a legitimate extension of Microsoft Icon Files and that are coded in the icon file format. Many webmasters have changed their preferred image's extension to .ico without first actually converting them to Microsoft Icon Files. This created a conflict that Microsoft Internet Explorer cannot resolve. Microsoft Internet Explorer will not display the fake icon images.

Icon files can be checked by viewing them in Microsoft Internet Explorer: if it displays the image, it is a legitimate extension, if no image was displayed with an "x", then it is a fake extension. By converting desired images to Microsoft Icon Files with manipulating softwares such as the GIMP, Photoshop, or the like that are truly able to convert or save images as Microsoft Icon Files, Microsoft Internet Explorer will display the icons.

Most modern browsers implement both methods of Favicon support.

[edit] Standardization

The original favicon feature was created by Microsoft for Internet Explorer which would request a favicon from a set 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 [1] 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. (viz. rel="shortcut icon")
  • The ".ico" file format (a raster format used for icons on Microsoft Windows) did not have a registered MIME type and wasn't likely to be automatically understood by most web browsers. In 2003, however, the format was registered with the Internet Assigned Numbers Authority (IANA) under the MIME type image/vnd.microsoft.icon, eliminating the first part of this problem.
  • The use of a reserved location on a website conflicts with the Architecture of the World Wide Web and is known as link squatting or URI squatting.

The Mozilla web browser added support for favicons in a way that conformed to web standards through the use of rel="icon" and letting web designers add favicons in any supported graphics format, e.g. <link rel="icon" type="image/png" href="/path/image.png" />. Most web browsers have since added support for this feature, and it is generally used for all new content.

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