ASP+ provides a series of new server controls that can be instantiated within an ASP+ page. From the developer's point of view, the advantage of using these controls is that server-side processing can be carried out on events raised by client-side controls.

The server controls provided with ASP+ fall into four broad categories or 'families':

• Intrinsic controls that create HTML-style elements on the client. They can create intelligent controls that automatically maintain state and provide extra features, or just plain HTML elements.
• List controls that can automatically produce lists of all kinds on the client. In conjunction with server-side data binding, they can also populate the lists with data from databases, XML files, etc. – using only a few lines of code.
• Rich controls output client-side HTML, and in some cases client-side script as well, in order to create more complex types of controls or interface elements on the client. An example is the 'Calendar' control, which detects the browser type and creates corresponding code to complement the features of that browser.
• Validation controls are non-visible controls that make it easy to do client-side or server-side validation when creating forms for the user to fill in and post back to the server. There is a range of these controls, allowing complex validation to be carried out easily.

All of these controls are designed to produce output that can run on any Web browser (you'll see this demonstrated in several places within the book). There are no client-side ActiveX controls or Java applets required. We'll look at each of these control types in more detail next.