Microsoft ASP.NET is more than the next version of Active Server Pages (ASP); it is a unified Web development platform that provides the services necessary for developers to build enterprise-class Web applications. It takes the best from Active Server Pages (ASP), as well as the rich services and features provided by the common language runtime and adds many new features.
While ASP.NET is largely syntax-compatible with ASP, it also provides a new programming model and infrastructure that enables a powerful new class of applications. You can augment existing ASP applications by incrementally adding ASP.NET functionality to them.
The basis of ASP.NET is Web Forms. Web Forms are the User Interface (UI) elements that give your Web applications their look and feel. Web Forms are similar to Windows Forms since they provide properties, methods, and events for the controls that are placed on them. UI elements render themselves in the appropriate markup language required by the request, e.g. HTML. If you use Microsoft Visual Studio .NET, you will also get the familiar drag-and-drop interface used to create a UI for your Web application. The following figure shows an overview of how ASP.NET works.
Web Forms are made up of two components: the visual portion (the ASPX file), and the code behind the form, which resides in a separate class file.
Web Forms and ASP.NET were created to overcome some of the limitations of ASP. These new strengths include: