php - Why is better to use filter_input()?

This should be a elementary question but why is better to use something like this:

$pwd = filter_input(INPUT_POST, 'pwd');

Instead of just:

$pwd = $_POST['pwd'];

PS: I understand that the filter extension can be used with more arguments to provide an additional level of sanitization.

Answer

It's not. $_GET, $_POST, $_COOKIE and $_REQUEST are filtered with default filter. filter_input(INPUT_POST, 'pwd') without additional parameters also uses the default filter. So there is no difference at all.