querystring question?

I was on a php site the other day they had links like this: www.??.com/somepage.php?variable=value but when you clicked on the link the address bar only had the page, not the querystring www.??.com/somepage.php How did them remove the querystring from the address bar. The only idea I had was they load the page, saved the querystring variables into session variables then used the header function to call itself again without the querystring. Thus to the eye, the querystring disappears from the address bar. Is there any other ways of doing this. Other then the way I explained above or by using a form with a POST method. Thanks, Mark.