What is the best approach to linking existing HTML files to PHP scripts for a website, without discarding the HTML files?

When linking existing HTML files to PHP scripts for a website without discarding the HTML files, you can use PHP's include or require functions to incorporate the PHP scripts within the HTML files. This way, you can maintain the structure and content of the HTML files while adding dynamic functionality through PHP scripts.

<?php
// Include the PHP script within the HTML file
include 'script.php';
?>