All controls residing inside the UpdatePanel will be partial postbacked.An UpdatePanel control is a holder for server side controls that need to be partial postbacked in an ajax cycle.The UpdatePanel enables you to add AJAX functionality to existing ASP.NET applications. It can be used to update content in a page by using Partial-page rendering. By using Partial-page rendering, you can refresh only a selected part of the page instead of refreshing the whole page with a postback.
