It is arguable whether the Façade pattern is a design pattern or not but it sure is a nice tool method for software developers. Since it occupies space both in GOF and Head First, I am also including it. The definition of Façade pattern according to mighty GOF is 

Provide a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use.

Seems easy isn't it, façade acts as a gateway for a series of complex procedures you need to do. All you have to do is delegate everything to your façade and use it as a gateway. If you need to call a specific method in the complex system, they are still available, just call them whenever you need. 

    public class Clothes{
         private int amount;
         private String owner;
         private String status;
         ...
    }

    public class WashingPresets {
        private WashingMachine washingMachine=new WashingMachine;
        public Clothes lightWash(Clothes clothes) {
             washingMachine.getWater(50);
             washingMachine.getDetergent(20);
             washingMachine.wash(clothes);
             return clothes;
        }
        public Clothes heavyWash (Clothes clothes){
             washingMachine.getWater(100);
             washingMachine.getDetergent(35);
             washingMachine.wash(clothes);
             washingMachine.getWater(100);
             washingMachine.getDetergent(40);
             washingMachine.wash(clothes);
             washingMachine.dry(clothes);
             return clothes;             
        }
        public Clothes normalWash(Clothes clothes) {
             washingMachine.getWater(100);
             washingMachine.getDetergent(40);
             washingMachine.wash(clothes);
             washingMachine.dry(clothes);
             return clothes;
        }
    }

 
    public class Client{
         // anyone who wants to use our washing machine can just use such a simple code piece
         public void washMyClothes(){
               Clothes clothes=new Clothes();
               WashingPresets ws=new WashingPresets();
               ws.heavyWash(clothes);
         }
    }

    public class TroublesomeClient{
         public void washMyClothes(){
               Clothes clothes=new Clothes();
               WashingPresets ws=new WashingPresets();
               WashingMachine washingMachine=new WashingMachine;
               ws.lightWash(clothes); //façade call
               washingMachine.getWater(50); //native methods call
               washingMachine.wash(clothes); //native methods call
         }
    }