$_POST['anyname']
and $_POST['anyage']
are sent automatically by PHP.
Previously $_SERVER superglobal was used.Here superglobal $_POST is introduced that has entire POST data.Here,from method is POST. If GET method is used, then the information of form would have been stored in $_GET superglobal instead.
Superglobal $_REQUEST can also be used, if source of request data is not taken into consideration. It possess the merged data of GET, POST and COOKIE.