Classes are containers. Objects are containers too. 

Classes are definitions of objects. Like a blueprint. 

Objects are instances of classes, actual realizations of that. 

Objects contain data and methods. They are called instance members. 

Examples of classes: Car, Person, President, Table.

Examples of objects: Car gh = new Car("Jason"); 
                     President w = new President("Bush");
                     Person o = new Person("Barack"); 

What members do you see in an object of type Table? 

http://www.yankodesign.com/images/design_news/2007/08/03/printer_table.jpg

class Table {
  Leg a, b, c, d; // instance variables
  Top t;          // instance variables
  Drawer d;       // instance variables
  void openDrawer(int distance) { // instance method 
    // we are going to change the state of this.d here 
  } 
}

class Leg {
  int height; 
  Color c;
  Finishing f;
  // there could be further methods here 
}

class Drawer {
  ...
} 


Methods, functions, procedures, subroutines: same thing. 

Classes may contain more than blueprint of objects. 

Components of the object blueprints are called: instance members. 

Members = variables and/or methods. 

Let's model a Horse: 

class Horse {
  void talk() {
    System.out.println("Howdy"); 
  } 
} 

class Program {
  public static void main(String[] args) {
    Horse a = new Horse();
    a.talk();
    Horse b; 
    b = new Horse(); 
    b.talk(); 
  } 
}

class Unicorn extends Horse {
  Horn h; 
} 

class Horn {
  // ...
}

Horse = {Tail, Leg, Leg, Leg, Leg, Mane, Head, Eye, Eye, ..., talk() }

Unicorn = Horse U { Horn } 

--------------------------------

class Horse {
  void talk() {
    System.out.println("Howdy");
  } 
}

class Unicorn extends Horse {

} 


class Program {
  public static void main(String[] args) {
    Horse a = new Horse();
    a.talk(); 
    Unicorn b = new Unicorn(); 
    b.talk(); 
  } 
}

A = {a, b, c}

B = A U {x, a}

This results in a resolution mechanism called dynamic method lookup.