title: little depth of session in php
body: <p>i've few questions about PHP sessions. hope to get the answers soon.</p>
  
  <ol>
  <li><p>if i'll only use session with out creating any cookies. does the session automatically create cookies at client browser?</p></li>
  <li><p>how to know the session id? is it created by the developer or each session created is referenced by an id?</p></li>
  <li><p>if i'll destroy a session, before destroying do i've to delete the cookies also for which i never written code in my site? (as i need to create only one time log in may b once in a year like election. so i don't need to store user information at client.)</p></li>
  <li><p>if my code will be <code>$_SESSION['user']='xxx'</code>, when 'yyy' logs in, does the <code>$_SESSION['user']</code> gets replaced by 'yyy' as the session data is stored in server?</p></li>
  <li><p>how do i know, how many simultaneous users can my site handle? does this has anything to do with how i manage the sessions? or server traffic?</p></li>
  <li><p>i read somewhere that sessions can also be hijacked. and hence suggested to store sessions in database instead of /tmp in server. how to store sessions in database? is there any specific process or we have to proceed like classical way, writing a query to insert when the session is created and deleting it when session is destroyed?</p></li>
  </ol>
  
  <p>thanks in advance.</p>