Enter Certificate ID: <?php // Check if the form is submitted if ($_SERVER["REQUEST_METHOD"] == "POST") { // Sanitize the input $certificate_id = filter_input(INPUT_POST, 'certificate_id', FILTER_SANITIZE_STRING); // Process the certificate ID (e.g., validate against a database) // For demonstration, we'll just echo the ID if (!empty($certificate_id)) { echo "

Certificate ID: " . htmlspecialchars($certificate_id) . "

"; } else { echo "

Please enter a valid Certificate ID.

"; } } ?>