Think about computation in terms of a collection of collaborating OBJECTS
* Objects can send messages to each other
* Objects have mechanisms for responding to messages

What is an object?
* A collection of
  * Data
  * Message handlers

More important stuff
* We group objects into CLASSES
  * Classes provide the general characteristics and handlers
    * All humans have a height
  * Objects have individual details
    * The Human SamR is 5'11" tall
* We can provide a hierarchy of classes
  * All humans are mammals
  * All mammals are animals
  * All animals are living creatures
  
* Three important chacteristics of oop
  * Encapsulation: We group data and algorithm and therefore 
    hide the inner workings
  * Inheritance: Support code reuse by using the hierarchy
  * Polymorphism: We can write a method that works with multiple kinds of things

OOP Languages need:
* Way to define classes
  * Data (fields)
  * Handlers (methods)
* Way to instantiate objects in classes
* Way to specify inheritance hierarchy
* Way to invoke handlers / call methods / send messages
* Way to OVERRIDE methods

WHAT IS THIS JUNK?