access like GET, POST or HEAD. The second argument references the URI source to read from. In this example the resource is a text file, later it will be a HttpServlet. Note that JavaScript security, also referred to as the JavaScript sandbox, doesn't allow you to access any other server than the one the code is downloaded from. The third argument is a Boolean type that defines whether the call should be synchronous (false) or asynchronous (true). Using synchronous requests will makes the browser wait for the serve to respond, which is not what you want to see happening in a production application when fetching lot of data from the server. You will use asynchronous server access later in this hands-on. The requestObject.send(null)&gt; method call on the XmlHttp Request object sends the request to the server. If this was a POST request, then the null argument value could be replaced with a list of request parameters that for the server to work with. Because this example uses a synchronous server call, the browser waits for the server response before proceeding. The http code send by the server on success of the request is 200. The success condition is checked with requestObject.status==PAGE_SUCCESS before the server response is read from the requestObject using a call to requestObject.responseText , which is method exposed on the XmlHttpRequest object. The rest of the code references a DIV HTML element on the page that is accessible through the DOM tree and that is used to display