"Pro ASP.NET 3.5 Server Controls and AJAX Components"
The controls are factored into three primary namespaces in the .NET Framework: System.Web.UI, System. eb.UI.HtmlControls, and System.Web.UI.WebControls (see Figure 1-8). 14 CHAPTER 1 ?– SERVER CONTROL BASICS Figure 1-8. The major namespaces of ASP.NET under System.Web.UI The System.Web.UI Namespace At the top of the hierarchy is our first destination??”the System.Web.UI namespace and its root controls. It contains the Control class, which is the mandatory parent class for all objects that want to call themselves controls. Directly inheriting from the Control class in this namespace is a set of specialized classes that implement the web form through the Page class, the user control through the UserControl class, and the literal controls. The Page class and the literal controls are discussed in detail in the previous ???Hello, World??? web form demonstration. We focus in more detail on the UserControl class in the next chapter when we cover control creation. System.Web.UI.HtmlControls Namespace The controls under System.Web.UI.HtmlControls have the capability to take existing HTML content and make it available as a server control with the addition of a runat="server??? attribute. The canonical example of this type of control is turning an HTML text box into a server control: