title: Push changes to a webpage without refreshing
body: <p>I know that we can do this by polling for changes in regular intervals. And this can be achieved by AJAX (for example using <code>jQuery.load()</code> along with <code>setInterval()</code> ). </p>
  
  <p>But I want to know that are there other methods to do this? Other less costly methods or more efficient methods? What logic an awesome chat client follows? As as soon as you start typing, the other end gets to know that you are typing. </p>
  
  <p>What mechanism do we follow here on stackoverflow to update the upvote count or to show that an edit has been made etc. etc. without the page being refreshed?</p>