object-oriented vocabulary review

• An object is an instance of a class.

• A class often has both instance and class variables and instance and class methods.

• A subclass (a.k.a. derived class) has all of the variables and methods of its superclass (a.k.a. parent class) and, usually, more. We say the subclass inherits these variables and methods from its superclass.

• When an instance or class receives a message, a method describes how it reacts, i.e. what operations it performs and what it returns.