I've noticed, that with Windows and IE, - when going to a page with characters for a script for which fonts are not installed my system, IE will sometimes ask whether or not I want to download & install fonts for that script from Microsoft's web site.
This only happens in some cases - even where the same script is involved. I've looked the source of some of these pages but I've never been able to identify just what what triggers this. Does anyone know?
I think M$ bases their guesses on what to download on the charsets used. If e.g. EUC-JP is used, you may be asked to download a Japanese fount, even if the page doesn't contain any Japanese characters at all, but it a Japanese page is encoded as UTF-8 (or even as Latin-1 with NRCs), you are not asked to download any Japanese fount. I haven't used M$ IE for many years, though, and my memory might be wrong.
Stefan