What is the recommended approach for handling content in HTML files in a PHP project?

When handling content in HTML files in a PHP project, it is recommended to separate the content from the presentation by using a templating system like PHP's `include` or `require` functions. This allows for easier maintenance and updates to the content without having to modify the HTML files directly.

<?php
// content.php
$content = "This is some dynamic content.";
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>PHP Project</title>
</head>
<body>
    <header>
        <h1>Welcome to our website</h1>
    </header>
    
    <main>
        <p><?php echo $content; ?></p>
    </main>
    
    <footer>
        <p>© 2022 PHP Project</p>
    </footer>
</body>
</html>