Q: What is a Favicon?
Favicon (short for "Favorites icon") is also known as a page icon or favicon.ico.
A Favicon is a multi-resolution image included on nearly all professional developed sites. Within Internet Explorer the Favicon is displayed on the Address line and in the Favorites menu. The Favicon allows the webmaster to further promote their site, and to create a more customized appearance within a visitor's browser. Often, the Favicon reflects the look and feel of the web site or the organization's logo.
Find more technical details at Wikipedia
Q: What is an ICO file?
An ico file is actually a repository of bitmap like images. They are used because in some locations a 16x16 pixel image is desired, and sometimes a 32x32 image may be needed. Sometimes a 16 color image is desired, and sometimes a 256 color icon is desired. This repository is scanned for the image size/color count appropriate for the location and the computer's color capability. If the image is not ideal, it may be compressed, expanded, and/or colors may be modified producing unexpected results.
Q: Isn't an ICO file just a renamed BMP?
NO. Although some people have said an ico is a BMP, this is not true. Think of an ICO file as a repository of BMP images. It has its own format. If you have a bmp image file you want to convert, use the free FavIcon Generator
on our web site to convert it to the proper ICO format.
Q: Is it necessary to name the favorite icon file as "favicon.ico"?
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"?
If you look around the Internet, you will notice that all professional web sites use FavIcons. A quality FavIcon gives your website instant brand recognition and a professional feel. Your FavIcon will be visible in visitor web browsers and gives a distinct look to your site in the Bookmarks menu helping to remind people to re-vist your site later.
Q: How do some websites have strange FavIcons with different sizes?
FavIcons (facicon.ico), as any other icon file, does not have to be a single image.
ICO files are an archive or repository, and can hold several different images,
all in one file - including simpler images for different color depths or larger or animated images for placement on the desktop.
Q: What is that "favicon.ico not found" error that is filling my site error.log?
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 search for. So, having a FavIcon favicon.ico will stop the entries in the error log.
Q: What browsers support FavIcons "favicon.ico"?
All current versions of the major browsers support favicons,
including Internet Explorer 5/6+, Firefox 1+, Mozilla 1+, Netscape 7+, Opera 7+, Konqueror 3+, Safari etc....