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# 9.5 Implementation vs. Interface Inheritance

### Interface Inheritance vs Implementation Inheritance <a href="#interface-inheritance-vs-implementation-inheritance" id="interface-inheritance-vs-implementation-inheritance"></a>

How do we differentiate between "interface inheritance" and "implementation inheritance"? Well, you can use this simple distinction:

* Interface inheritance (what): Simply tells what the subclasses are able to do.
  * EX) all lists should be able to print themselves, how they do it is up to them.
* Implementation inheritance (how): Tells the subclasses how to implement their behavior.
  * EX) Lists should (by default) print themselves exactly this way: by getting each element in order and then printing them.