Polymorphism is what's doing

Polymorphism, a subclass inherits a parent class, with the function name of the parent class, then not achieve the same function.

Often is the parent class defines a function name, but do not write achieve. Who inherits the parent class, you write your own implementation.

 

So that the same function name, between different sub classes, subclasses, and between the parent class, the functions of different called polymorphism.