1. OO Programming is about conventions for handling local state: ? What is in the state. ? How access is granted to the state. ? How is the state created, initialized, and modified. ? How code for handling the state can be shared for reuse. 2. Terminology: Access to state is via objects. An object can send and receive messages, and has access to various methods for responding to them. 3. Terminology: Objects are created by classes, which specify what state is to be created when a new object is created, what messages the object will process, which methods it will use to process those messages, and what to do if the object receives a message for which it has no method. 4. The classes are related to each other through inheritance or delegation. We’ll explore delegation (it’s a bit more powerful) but Java uses inheritance. 5. In Scheme, objects and classes are both procedures. The local state is stored in the frames that are created when the procedures are called. This is also true of Java.