When a child class overrides a member, it defines a new version for a member that is already defined in the parent class.
For example, suppose that you have defined the Person and Employee classes described in the previous section, and that the Person class defines the AddressEnvelope method. Now, suppose that you add a new MailStop property to the Employee class. In that case, you can override the AddressEnvelope method in the Employee class so that it prints the address with the MailStop added.
Now, if the code calls AddressEnvelope for a Person object, the original version of the method executes. If the code calls AddressEnvelope for an Employee object, the new version of the method executes.
The really amazing thing about overridden ...