The first is the method shown in the preceding samples, where the page code is physically declared within the originating .aspx file. The following sample demonstrates the use of the code-behind method of writing ASP.NET page code. ASP.NET Web Forms pages provide syntax compatibility with existing ASP pages. ASP.NET server controls provide an easy way to encapsulate common functionality. ASP.NET ships with 45 built-in server controls.
Developers can also use controls built by third parties.
ASP.NET templates provide an easy way to customize the look and feel of list server controls. ASP.NET validation controls provide an easy way to do declarative client or server data validation.