Microsoft ASP.NET is a free technology that allows programmers to create dynamic web applications. ASP.NET can be used to create anything from small, personal websites through to large, enterprise-class web applications. All you need to get started with ASP.NET is the free .NET Framework and the free Visual Web Developer. Using AJAX in ASP.NET pages can increase performance and improve the overall user experience of an application. It is not necessary to rewrite existing pages to add AJAX features. With only a few modifications, an existing ASP.NET page can be made to use AJAX. This video demonstrates how to add AJAX functionality to an existing ASP.NET page with minimal effort.