Cross Page Posting In ASP.NET
Each web server control has its own properties and events. On firing event of control, webpage will post back to the same page by default. This is part of the round-trip cycle that ASP.NET Web pages go through as part of their normal processing.
Under some circumstances, you might want to post one page to another page . In this case, you can configure certain controls on the page to post to a different target page via an HTTP 302 (i.e. Response.Redirect). That means, it is the concept which is used to submit one page (source.aspx) controls to another page (destination.aspx) and access those page (source.aspx) control values in another page (destination.aspx). So, cross page posting enables you to post the WebPage and WebPage's control values to another WebPage.
In Cross page posting , on click of a button there would be no return trip.