Chapter 7 - Implementing Interfaces and Inheriting Classes

1. What is a delegate?
   • A delegate is a type-safe method reference. It can be used to execute any method with a matching signature.
2. What is an event?
   • An event is a field that is a delegate having the event keyword applied. The keyword ensures that only += and -= are used; this safely combines multiple delegates without replacing any existing event handlers.
3. How is a base class and a derived class related?
   • A derived class (or subclass) is a class that inherits from a base class (or superclass).
4. What is the difference between the is and as operators?
   • The is operator returns true if an object can be cast to the type. The as operator returns a reference if an object can be cast to the type; otherwise, it returns null.
5. Which keyword is used to prevent a class from being derived from, or a method from being overridden?

           sealed 
   

   • Find more information on the sealed keyword at https://msdn.microsoft.com/en-us/library/88c54tsw.aspx
6. Which keyword...