Do search engines interpret PHP code or only the output visible to users?

Search engines only interpret the output visible to users, not the actual PHP code itself. To ensure that search engines can properly index your website, it's important to have clean and semantic HTML markup that includes relevant keywords and content. Additionally, using server-side rendering techniques can help ensure that search engines can access and index your website's content effectively.

<?php
// PHP code snippet that generates HTML output visible to users
echo "<h1>Welcome to my website!</h1>";
?>