How can the use of iframes impact the functionality of PHP forms and header modification?

When using iframes to embed PHP forms, it can impact the functionality of the forms as the headers might not be modified correctly due to the iframe encapsulation. To solve this issue, you can set the X-Frame-Options header to deny in the PHP script to prevent the page from being embedded within an iframe.

<?php
header("X-Frame-Options: deny");
?>