What is the significance of the PHP setting register_globals and how does it affect the usage of variables like $submitted?

The significance of the PHP setting register_globals is that it determines whether global variables, such as form input variables like $submitted, are automatically registered as PHP variables. This setting can pose security risks by allowing external input to overwrite existing variables. To mitigate this risk, it is recommended to disable register_globals and manually retrieve form input using superglobal arrays like $_POST or $_GET.

// Disable register_globals in PHP configuration
// Manually retrieve form input using $_POST or $_GET
$submitted = isset($_POST['submitted']) ? $_POST['submitted'] : '';