Objects and messages. Expression syntax. Classes and instances. Subclasses. Metaclasses. Protocol for all objects. Linear measures. Numerical classes. Protocol for all collection classes. Hierarchy of the collection classes. Three examples that use collections. Protocol for streams. Implementations of the basic collection protocol. Kernel support. Multiple independent processes. Protocol for classes. The programming interface. Graphics Kernel. Pens. Display objects. Probability distributions. Event-driven simulations. Statistics gathering in Event-drive simulations. The use of reesources in event-drive simulations. Coordinated resources for event-drive simulations. The implementation. Specification of the virtual machine. Formal specification of the interpreter. Formal specification of the primitive methods. Formal specification of the object memory. Subject index. System index. Example class index. Implementation index.