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. In this ASP.NET video tutorial, you'll learn how to develop the basics of a custom extender control using the ASP.NET extensions framework. Get started using ASP.NET extensions to create extender controls with this how-to.