Register Globals

Register globals is an old and removed feature of PHP, which automatically created variables from the incoming super globals, such as $_GET, $_POST, $_REQUEST, $_COOKIES.

This meant that the initial set of variables in an application was not known, as they would depend on the incoming data.

Register-globals has been removed in PHP 5.4.

<?php
     // $_GET['foo'] = 'bar';

     echo $foo;

     // $_GET['_SESSION']['logged'] = '1';

?>

Documentation