Class hierarchy

• A class can have several subclasses. For example, we could define a subclass ExpertPerson of Person, whose objects represent persons that are experts in a certain topic, where the topic in which they are experts is a specific property of the class.
• A subclass of a class can itself have subclasses. For example, the class Student derived from Person could have a subclass WorkingStudent.
• Hence, using several derivations, it is possible to create hierarchies of classes.