In PHP manual, the description for session_destroy() function is :session_destroy() destroys all of the data associated with the current session. It does not unset any of the global variables associated with the session, or unset the session cookie. To use the session variables again, session_start() has to be called.I am confused about this description. If this function destroys all session data, then why the global variables associated with the session are not unset? Why can we use the session variables again?If we read the description carefully, we can find what this function does...