This document discusses classes and objects in Java. It explains that in Java, all programs are based on classes which define the state and behavior of objects. Classes create objects and objects use methods to communicate. A class is a collection of fields (data) and methods (procedures or functions) that operate on that data. A class declaration specifies the class name, extends any superclasses, and contains field and method declarations. Methods are declared inside the class body after data fields. Objects are created dynamically using the new keyword and the class name.