title: What is ASPNET GUID?
body: <p>I have seen this code in ShoppingCart class in Music Store MVC3 tutorial: <a href="http://www.asp.net/mvc/tutorials/mvc-music-store" rel="nofollow">http://www.asp.net/mvc/tutorials/mvc-music-store</a></p>
  
  <pre><code>// We're using HttpContextBase to allow access to cookies.
          public string GetCartId(HttpContextBase context)
          {
              if (context.Session[CartSessionKey] == null)
              {
                  if (!string.IsNullOrWhiteSpace(context.User.Identity.Name))
                  {
                      context.Session[CartSessionKey] =
                          context.User.Identity.Name;
                  }
                  else
                  {
                      // Generate a new random GUID using System.Guid class
                      Guid tempCartId = Guid.NewGuid();
                      // Send tempCartId back to client as a cookie
                      context.Session[CartSessionKey] = tempCartId.ToString();
                  }
              }
              return context.Session[CartSessionKey].ToString();
          }
  </code></pre>
  
  <p>Why is GUID needed? I am asking for somebody to explain what is it used for in this example.</p>