A Smalltalk shares a class with similar objects
Each object has special distinguishing values that are called its instance variable:
Classes define what set of instance variables are valid for their objects.
Classes also determine the way that their objects react to messages. They assoicate each message selector with a method for handling it. The set of possible messages for a class is called its protocol:
Each method has
A message has a selector and an array of arguments;
Sending a message to an object produces another object: