Events are handled by delegates. An event listener supplies an event-handler delegate that is invoked whenever the event is raised by an event source. In order to connect to the event source, the event listener adds this delegate to the invocation list of the source. When the event is raised, the event-handler delegate invokes the methods in its invocation list. The EventInfo.GetAddMethod, EventInfo.AddEventHandler(object, Delegate) , EventInfo.GetRemoveMethod, and EventInfo.RemoveEventHandler(object, Delegate) methods, and the delegate type of the event-handler associated with an event, are required to be marked in the metadata.