Traditionally when a Web page is requested, the user must wait while the entire page is retrieved from the server after which the
complete page appears suddenly in the browser. This video demonstrates how the AJAX Incremental Page Display Pattern improves the user
experience by quickly and smoothly fetching and displaying portions of the Web page.
文章来源:http://www.asp.net/learn/videos/view.aspx?tabid=63&id=118