I don't understand why do we need the "event" keyword while defining events, when we can do the same thing without using "event" keyword, just by using the delegates.

e.g.

public delegate void CustomEventHandler(int a, string b);
public event CustomEventHandler customEvent;
customEvent += new CustomEventHandler(customEventHandler);
customEvent(1,"a"); // Raising the event

Here if I remove the "event" keyword from the second line, then also I can raise the event by invoking the delegate. Can anybody please tell me why is this event keyword needed ?