title: Client side message functionality
body: <p>How the ilusion of causing site to change content from server side is done? Let the example be gmail chat or chat on facebook. Or even new message sign on stack overflow.</p>
  
  <p>Is it done by <a href="http://en.wikipedia.org/wiki/Comet_(programming)" rel="nofollow noreferrer">http://en.wikipedia.org/wiki/Comet_(programming)</a>) ?</p>
  
  <p>Thanks for help</p>