How do javascript non-reliant sites serve up database driven webpages?

Sorry if this seems like a stupid question.

I understand that it is good practice to have your site work without javascript, since javascript can and will be disabled, and some older devices don't support javascript.

I also understand that a great number of database driven sites (such as facebook's mobile view) generate the html page and all the user specific content server side and then serve the webpage to the user, so javascript is not needed to render the page correctly.

At present I've been relying on serving the same page up to each user and then filling it with their content by making HTTP GET requests with javascript and then rendering the content in javascript.

My question is how are pages requested without javascript? Facebook's mobile site just immediately renders your customised page assuming you've logged in before, how has the front end page itself detect you've logged in before, authenticate you with the server and request your custom page all without javascript and before the page has even loaded? Is the default answer always php? I've heard that php is old and sites like facebook are moving away from it, what are the alternatives?