ASP.NET Web Server Controls
ASP.NET Web server controls are objects on ASP.NET Web pages that run when the page is requested and that render markup to the browser. Many Web server controls are similar to familiar HTML elements, such as buttons and text boxes. Other controls encompass complex behavior, such as a calendar controls, and controls that you can use to connect to data sources and display data.
ASP.NET also provides AJAX-enabled server controls. These consist of server and client code that integrate to produce rich client behavior. When you add an AJAX control to an ASP.NET Web page, the page automatically sends supporting client script to the browser for AJAX functionality. You can also provide additional client code to customize the functionality of a control, but this is not required.
The topics in this section describe what ASP.NET Web server controls are and how to work with them.