An ASP.NET Web Form can contain any or all of the following types of server controls:

HTML server controls

Programmable HTML controls. HTML server controls expose an object model that maps very closely to the HTML elements that they render.

Web server controls

Programmable controls with more built-in features than HTML server controls. Web server controls include not only controls for user input, but also special-purpose controls such as a calendar, menus, and a tree view control. Web server controls expose an object model specifically intended for programming Web pages.

Validation controls

Controls that incorporate logic to allow validation of user input. Validation controls enable checking for a required field, and testing against a specific value or pattern of characters, between ranges, and so on. For more information about validation controls, see Web Forms Validation.

User Controls

User-defined controls that are mainly used for embedding in other ASP.NET Web pages. User controls provide an easy way to create reusable page elements, such as a search box with built-in user-defined search logic. For more information about user controls, see Web Forms User Controls.

NOTE: You can also create output for mobile devices. To do so, you use the same ASP.NET page framework, but you create Mobile ASP.NET Web pages instead of ASP.NET Web pages and use controls specifically designed for mobile devices. For details, see Creating ASP.NET Mobile Web Applications.

Now let’s briefly explore the main features of each type of server control.