Server controls: The server controls are Hypertext Markup Language (HTML) elements that include a runat=server attribute. They provide automatic state management and server-side events and respond to the user events by executing event handler on the server. HTML controls: These controls also respond to the user events but the events processing happen on the client machine. Data controls: Data controls allow to connect to the database execute command and retrieve data from database. System components: System components provide access to system-level events that occur on the server.