1. Here is the group chat page, a very simple Ajax example.
   1. The chat page: [ Group Chat Source ]
   2. The supporting PHP script: [ Message Collector Source ]
2. Things to note.
   1. The page is updated by Javascript: it is not reloaded.
   2. But it does get information from the server: Javascript uses an an HTML request using the XMLHttpRequest Javascript object.
      1. Starts the request.
      2. Arrival of a response is an event that must be handled later.
   3. The HTTP request is handled by a specialized PHP script.
      1. The script does not return an HTML page, but either plain text, or JSON.
      2. The response is consumed by the javascript, not parsed by the browser.