Whenever, you need to deal with the first webpage's control value to different pages of your application , you can do this with cross page posting. So, cross page posting enables you to post the WebPage and WebPage's control values to another WebPage in your asp.net applications.
There are two ways we can use cross page postsbacks in ASP.NET
Suppose you have some controls like textboxes, labels and one button on your first page -
Text="Submit Page to secondpage.aspx"
use PostBackUrl and assign the url of second page.
Now on the second page, using PreviousPage property you can receive those values of controls from your first page.