Showing up variables in URL !

Hello ! We all know how to pass value to variable using an URL. So, how can I do the inverse ? I mean , showing the value of a variable in the URL? for instance my page "index.php" is : <? $greetings="Hello" ; echo $greetings ; ?> So, how to make PHP so that when I load my page in the browser(typing "index.php" in the adress bar) , it will print not only "hello" on the page,but also show "index.php?greetings=hello" as URL .... , So , I basically want PHP to dynamically append "?greetings=<?=$greetings?>" to the URL I've typed........ How to do this ? I hope I've made myself understood ... :o) Thanks... Arcad.