HTML server controls are HTML elements containing attributes that make them visible to — and programmable on — the server. By default, HTML elements on a Web Forms page are not available to the server; they are treated as opaque text that is passed through to the browser. However, by converting HTML elements to HTML server controls, you expose them as elements you can program on the server.
The object model for HTML server controls maps closely to that of the corresponding elements. For example, HTML attributes are exposed in HTML server controls as properties.
Any HTML element on a page can be converted to an HTML server control. Conversion is a simple process involving just a few attributes. As a minimum, an HTML element is converted to a control by the addition of the attribute RUNAT=”SERVER”. This alerts the ASP.NET page framework during parsing that it should create an instance of the control to use during server-side page processing. If you want to reference the control as a member within your code, you should also assign an ID attribute to the control.
The page framework provides predefined HTML server controls for the HTML elements most commonly used dynamically on a page: forms, the HTML <INPUT> elements (text box, check box, Submit button, and so on), list box (<SELECT>), table, image, and so on. These predefined HTML server controls share the basic properties of the generic control, and in addition, each control typically provides its own set of properties and its own event.
