fetching a parameter from url like on php.net A mirarcle?

Hi there, I am wondering how to get a parameter from url like on php.net Example: php.net/functionname I guess this is a server config isn't it? The server would otherwise asume this is a file and return a 404 error. How could I tell the server to run index.php if the file name is not on the server. And then .. how to get a 404 if this is not a function, but really a not existant page? Maybe someone of the php.net team could uncouver the miracle :-) Thanx Andy