title: What happens when I modify a session Id?
body: <p>I'm exploring cookies and sessions [I'm using them with respect to ASP.NET C# microsoft framework]</p>
  
  <p>Learnt how sessions and cookies work <a href="https://stackoverflow.com/questions/1401325/where-is-session-stored-if-cookie-is-disabled-on-clients-machine-what-is-actua?rq=1">here</a> and <a href="http://ejvyas.blogspot.in/2010/02/where-is-stored-is-it-in-browser-or-at.html" rel="nofollow noreferrer">here</a>.</p>
  
  <p>My take on it is like,</p>
  
  <ol>
  <li><p>Once a user logs in and establishes a session, he or she is given a session id to track them further.</p></li>
  <li><p>Also, this <code>sessionId</code> can be stored on a Server, like SQL Server or a InProc, meaning it is stored on the issuing server or on a cache, Redis Cache.</p></li>
  </ol>
  
  <p>My question is like, </p>
  
  <p>I can understand that the <code>sessionId</code> is stored in a memory and being sent with every request (since HttpSessions are stateless) as HttpHeaders. </p>
  
  <ol>
  <li>When we talk about storing sessions in a memory, which memory are we talking about ?</li>
  <li>If we are storing them in a cookie, what If I go and modify the cookie ?</li>
  <li>If I can modify them, what If I change the <code>sessionId</code> and supply in a new <code>sessionId</code> ?</li>
  </ol>