Ajax introduces a new approach to WebPages that update the portion of a the page by a techniques called Partial-page rendering. Partial-page rendering eliminate the traditional way of doing a full postback (full page refresh) to the web server and updates only the necessary portion of the web page. That is, only the necessary data is transferred back and forth between the client and the web server . Using this techniques you can cut down on the network load , bandwidth usage and moreover the web page is not locked during the server processing. It helps in creating faster, better, dynamic and interactive web applications.