title: How are notifications such as "xxxx commented on your post" get pushed to the front end in Facebook?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1086380/how-does-facebook-gmail-send-the-real-time-notification">How does facebook, gmail send the real time notification?</a>  </p>
  </blockquote>
  
  
  
  <p>For example, I am on Facebook and I see this little notification being displayed that some one commented on a post I made. What is the technology used here?</p>
  
  <p>Is it AJAX? If so how can data be PUSHED to the front using AJAX?</p>