Forwarding Requests 

You forward requests to be processed by another Web resource using the forward() method of the RequestDispatcher object. You may use request forwarding if you want to have a servlet that does some preliminary processing of the request, and then to forward it to another resource to generate a response and send it to the client. This is the major difference between the forward and the include requests – when you use forward()method, the content of the response that the first component has generated is ignored, and the second component generates the whole response and sends it to the client.

There is a restriction when using forward()method that you must observe in your servlet code. You must not have sent any content of the response in order to forward a request. If the response buffer of the initial servlet contains any response content, it is discarded.

If you use authentication for the resources of your Web application, it does not force a new security check when you forward a request to a protected resource.