Objects and classes in Java

• The objects are the entities that can be manipulated by programs (typically, by invoking their methods).
• Each object belongs to a class (we say that it is an instance of the class) .
• A class is constituted by a set of objects that have the same properties: its istances.
• The class to which an object belongs to determines which methods are available for (i.e., can be applied correctly to) the object. For example:

  System.out.print(); //OK
  System.out.foo();   //ERROR