Is PHP front-end or back-end?

The answer

PHP is a back-end language. It runs on the server, prepares the response and sends only the result to the browser, which then shows the page. The browser never receives your PHP instructions, which is why view source does not reveal them. The front end is what the visitor sees and uses, built with HTML, CSS and JavaScript. PHP often generates that front-end code, but it does not run in the browser itself.