title: I need to show which users are online for my AJAX Chat
body: <p>I have an inline chat application which I got from <a href="http://anantgarg.com/2009/05/13/gmail-facebook-style-jquery-chat/" rel="nofollow noreferrer">Ajax Chat</a>, which is working brilliantly. The application allows a user to chat with users that are registered on the system. Ie: <img src="https://i.stack.imgur.com/QSCXd.png" alt="Here is a list of the users"></p>
  
  <p>Now I need to show if the user is online or offline. </p>
  
  <p>So my question is how do I show online users using PHP?</p>
  
  <p>Thank You</p>