The use of the favicon.ico file, begun by Microsoft, raises certain privacy concerns.
Basically, as implemented by Microsoft, the favicon.ico mechanism allows web content developers to
know when someone likes a webpage enough to add it to a bookmarks list. Without offering any means to disable
this automatic notification, Microsoft opened the door for marketing analysts to determine exactly what content
would inspire people to return to a web page.
The use of the HTML <link> tag does not present the same privacy problem, because the icon it targets is downloaded
automatically when the web page is visited. If someone then adds the page to a bookmarks list, no revealing
download is necessary.