How does using frames affect search engine optimization in PHP projects?

Using frames in PHP projects can negatively impact search engine optimization (SEO) because search engines may have difficulty crawling and indexing content within frames. To improve SEO in PHP projects, it is recommended to avoid using frames and instead utilize modern web development techniques like responsive design and AJAX to create a more search engine-friendly website.

<!DOCTYPE html>
<html>
<head>
    <title>SEO-friendly PHP Project</title>
</head>
<body>
    <!-- Content without frames -->
</body>
</html>