HTML Server Controls
You can mark any HTML control to run as an HTML server control. Unlike regular HTML controls, HTML server controls are programmable on the Web server. You can access properties and events for the HTML server control just as you do for controls in Windows desktop-based applications.
HTML server controls are not as flexible in code as are Web Server controls. The main reason they exist is that they provide an easy migration path for existing HTML pages. To convert an HTML control to an HTML server control, right-click on it in Visual Studio .NET and select Run As Server Control.