a URL ending with something like
portal.php?key2=hello how can I get the value of “key2”?
var_dump( $_GET['key2'] );
will get you the value from a query string.
will get you the value from a form posted.
will get you either of the above if it exists.
GET data is decoded into the $_GET super-global array. See http://php.net/manual/en/language.variables.external.php