Can someone confirm that the is the basic flow for PHP - HTML.

PHP runs on the server, and pre-processes the page so it can be sent to the browser.

In the browser you can run things like javascript.

So in order to pass things to PHP (from Javascript):

you need to "fetch" the php page (with post or get args)
This re-runs the php page (on the server) allowing you to process those args, generating a new "page" to send to the browser. 
PHP variables aren't "sent" to the browser, but processed and inserted in the a new page that's sent out when the page is fetched.

Am I even close ?