title: $_SERVER['HTTP_USER_AGENT'] and session_regenerate_id in PHP
body: <p>After reading a great post on PHP session security .I have two questions from the discussion.</p>
  
  <p>1)$_SERVER['HTTP_USER_AGENT'] -This gets the information about the user's browser and other details and since a person can access their account from a different computer then how is it useful?</p>
  
  <p>2)session_regenerate_id - This regenerates   a session id , How should I use it ? Is the session_id deleted after a session has timeout or closed?</p>
  
  <p>Thanks for all your help.I appreciate each view and response.</p>