How can HTML variables be converted to PHP variables for further processing?

To convert HTML variables to PHP variables for further processing, you can use the $_POST or $_GET superglobals in PHP. These superglobals allow you to access form data that has been submitted using either the POST or GET method. You can then assign the values from the HTML form to PHP variables for further processing.

<?php
// Assuming a form with input field named 'username'
$username = $_POST['username'];

// Now you can use the $username variable for further processing
echo "Hello, $username!";
?>