Design Pattern are about design, interaction of objects, as well as providing a communication platform for objects and reusable solutions to common problems.
Design Pattern are important to understand for the following reasons:
1) They give us reuse.
2) Design Pattern allow one refer to a design concept without explaining the full detail.
3) They give us a common taxonomy(classification) allowing for better communication.
There are three type of pattern :-
1) Creational Pattern :- Based on how to create an object
2) Structural Pattern :- Based on how to define the structure using interface and abstract classes
3) Behavioral Pattern :- Based on communication of the object how do they communicate.