Privacy issues 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.