What PHP function would you use to direct a visitor to one page from another page if, for example, your script on the current page performs a test of some kind and decides the user should go to that...

What PHP function would you use to direct a visitor to one page from another page if, for example, your script on the current page performs a test of some kind and decides the user should go to that other page? What is the PHP feature called that you use to provide a way for certain information to be “remembered” as your site visitors browse from one page to another, and what is the first thing you need to do in a PHP script that wants to take advantage of this feature?