An event is just a wrapper for a multicast delegate. Adding a public event toa class is almost the same as adding a public multicast delegate field. In both
cases, subscriber objects can register for notifications, and in both cases the
publisher object can send notifications to the subscribers. However, a public
multicast delegate has the undesirable property that external objects can
invoke the delegate, something we’d normally want to restrict to the
publisher. Hence events – an event adds public methods to the containing
class to add and remove receivers, but does not make the invocation
mechanism public.