What is the difference between PHP and HTML?

The answer

HTML describes the structure and content of a web page, while PHP is a programming language that runs on the server and can generate HTML dynamically. A browser understands HTML directly but cannot run PHP, so the server runs the PHP first and sends only the resulting HTML. The PHP manual notes that PHP code can be embedded into HTML. Think of HTML as the page layout and PHP as the logic that fills it with the right content.