C# Version 1

• Declaring a delegate is similar to defining a class, struct, or interface. That is, we can define it inside or outside a class.
• A delegate type specifies the parameter and return types that methods must have.
• A delegate instance contains a list of methods that each have an appropriate signature.
• We usually add methods to the invocation list with the += syntax.
• When we invoke a delegate instance, we invoke all of its methods and receive the return value of the final method.
• We stop invoking the method list if any method throws an exception.
• Methods stored in a delegates invocation list have access to the members of the class that defined the method.

Events

• An event must be declared as a delegate type.
• We use += and -= to subscribe and unsubscribe to an event.
• When we do this, we are calling the Add/Remove methods on the event's delegate type.

Sources

C# in Depth, Third Edition, Jon Skeet