What is cross page posting?
By default, the button controls in the ASP.NET pages post back to the similar page that contains button, where you can write an event handler for the post. In most of the cases this is the desired behavior, but occasionally you will also want to be able to post to other page in your application. The Server. Transfer process can be used to move b/w pages, however the URL doesn't change. In spite, the cross page posting feature in ASP.NET 2.0 allows you to fire a normal post back to a different page in the application. In the target page, you can access the values of server controls in the source page that initiated the post back.
To use the cross page posting, you can set the PostBackUrl property of a LinkButton, Button or ImageButton control, which specifies the target page. In the target page, you can then access the PreviousPage property to retrieve the values from the source page. By default, the PreviousPage property is of type Page, so you must access controls by using the Find Control Process. You can also enable strongly-typed access to the source page by setting the @PreviousPageType directive in the target page to the virtual path or Type name of source page.
Here is a step-by-step guide for implementing the cross-page post back using controls that implement the IButtonControl interface.
1) Create a Web Form and insert a Button control on it using the VS .NET designer.
2) Set the button's PostBackUrl property to the Web Form you want to post back. For instance in this case it is "nextpage.aspx"