Navigate to other page:
You can insert a normal URL in this snip.
But you can also, with PHP, insert a PHP variable with an URL, into the string, and send people anywhere.
You don´t have to use this with a static URL.
I will sugges that you use a $_SESSION['myURL'] variables for making dynamic URL links in you web-program. With $_SESSION['myURL'] you can use the variable across pages in your project.