Ever had to change a favicon and you wanted to update it? The browser caches these icons for a long time and for good reason, because in general they don’t change that much.
<link rel=”shortcut icon” href=”favicon.ico”/>
<link rel=”shortcut icon” href=”favicon.ico?new”/>
It only works once per change, though. So if you change it again, replace ?new with something different, like ?new2.