There are two uses of & in HTML. First the one you know about: between > and < . There it codes foreign characters. And is itself a foreign character which must be coded. Now the second use: between < and > . There it separates arguments to CGI-scripts. There it should not be encoded.

Because other newbies confuse these two uses too, modern browsers can be instructed to use ; instead. Then you can use ; in your links too (the case between < and >).