Q: What is favicon.ico?
A: Favicon.ico (short for "Favorites icon"), also known as a page icon, is an icon associated with a particular website or webpage. 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 URL bar, next to the site's name in lists of bookmarks, and next to the page's title in a tabbed document interface. Find more technical details at Wikipedia.

Q: Is it necessary to name favorite icon file as "favicon.ico"?
A: The use of the "favicon.ico" file name is a default.
If you want, you may specify the filename for the favourite icon to be used for each particular page on your website,
so in theory you can have different favicons for each page.

Q: Why would I use "favicon.ico"?
A: If you look around the Internet, you will notice that all professional web sites use it. It gives more customized appearance of your site in visitor browser and it also gives more distinct look of your site in Bookmarks menu by replacing generic browser icon.

Q: How some sites has such strange favicon.ico with different sized images in it?
A: Facicon.ico, as any other icon file, does not have to be a single image.
It is an archive or repository, and can hold several different images,
all in one file — simpler images for different colour depths or larger images for placement on the desktop.
Look at the sample.

Desktop view with our favicon.ico:

Q: What is that "favicon.ico not found" error that is filling my site error.log?
A: Some browsers automatically looks for a favicon.ico file they think you should have whenever someone creates a bookmark or a shortcut to a page on your site. If you surf with Internet Explorer you've probably noticed that some of your bookmarked sites have custom icons while others have the default IE icon. Those custom icons are the favicon.ico that browsers is so diligently searching for. So, having favicon.ico will stop the entries in the error log.

Q: What browsers support "favicon.ico"?
A: Currently most modern browsers support it,
including Internet Explorer, Mozilla Firefox, Konqueror, Safari, Opera and Netscape.