What is the difference between an event and a delegate?

An event is just a wrapper for a multicast delegate.
Adding a public event to a 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.

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