title: What are session_id, session_regenerate_id and session_name used for?
body: <p>ok im a newbie on sessions lets imagine that we have a little login site,</p>
  
  <p>heres a logic</p>
  
  <ol>
  <li>login</li>
  <li>if password right = use $_SESSION[isaloginuser] = 1</li>
  <li>check session to see menus with if $_SESSION[isaloginuser] = 1</li>
  <li>show the menus</li>
  <li>the user want to logoff</li>
  <li>unset session</li>
  <li>destroy session system</li>
  </ol>
  
  <p>what it use</p>
  
  <pre><code>session_register
  session_destroy
  session_unset
  session_start
  </code></pre>
  
  <p>where does the <code>session_id</code> &amp; the <code>session_regenerate</code> or <code>session_name</code> goes in ? 
  at php site it says</p>
  
  <blockquote>
    <p>session_id() is used to get or set the
    session id for the current session.</p>
  </blockquote>
  
  <p>i still just dont get it, why do we need them anyway ? in <strong>real environment</strong> what does it do ?</p>