What are the potential pitfalls of using frames in PHP websites?

Using frames in PHP websites can cause issues with search engine optimization, as search engines may have difficulty crawling and indexing content within frames. Additionally, frames can create accessibility issues for users with disabilities, as screen readers may have trouble navigating content within frames. To avoid these pitfalls, it is recommended to use modern web development techniques such as CSS for layout and AJAX for dynamic content loading.

<!DOCTYPE html>
<html>
<head>
    <title>PHP Website without Frames</title>
    <style>
        /* CSS for layout */
    </style>
</head>
<body>
    <div id="header">
        <?php include 'header.php'; ?>
    </div>
    <div id="content">
        <?php include 'content.php'; ?>
    </div>
    <div id="footer">
        <?php include 'footer.php'; ?>
    </div>
</body>
</html>