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Controls are small building blocks of the graphical user interface, which includes text boxes, buttons, check boxes, list boxes, labels and numerous other tools, using which users can enter data, make selections and indicate their preferences.

Controls are also used for structural jobs, like validation, data access, security, creating master pages, data manipulation.

ASP.Net uses five types of web controls, which are:

• HTML controls

• HTML Server controls

• ASP.Net Server controls

• ASP.Net Ajax Server controls

• User controls and custom controls

ASP.Net server controls are the primary controls used in ASP.Net. These controls again could be grouped into the following categories:

• Validation controls - these are used to validate user input and work by running client-side script

• Data source controls - these controls provides data binding to different data sources

• Data view controls - these are various lists and tables, which can bind to data from data sources for display

• Personalization controls - these are used for personalization of a page according to the user's preference, based on user information

• Login and security controls - these controls provide user authentication

• Master pages - these provides consistent layout and interface throughout the application

• Navigation controls - these helps in navigation, for example, the menus, tree view etc.

• Rich controls - these implements special features, for example, AdRotator control, FileUpload control, Calendar control etc.

The basic syntax for using server controls is:

<asp:controlType  ID ="ControlID" 
                     runat="server" 
                     Property1=value1  [Property2=value2] />

However, visual studio has the following features, which helps in error free coding:

• Dragging and dropping of controls in design view

• IntelliSense feature that displays and auto-completes the properties

• The properties window to set the property values directly

Properties of the Server Controls

The ASP.Net server controls with a visual aspect are derived from the WebControl class and inherit all the properties, events and methods of this class.

The WebControl class itself and some other server controls that are not visually rendered, e.g., the PlaceHolder control or XML control etc., are derived from the System.Web.UI.Control class.

ASP.Net server controls inherit all properties, events and methods of the WebControl and System.Web.UI.Control class.

The following table shows the inherited properties, which are common to all server controls:

Methods of the Server Controls

The following table provides the methods of the server controls: