What is a Design Pattern?
Every Software Engineer certainly must have to deal with change. Change is a constant in Software Design: adding feature, changing of requirement or bug fixing.
What is a design pattern? In simplest way I can say, it is a general solution for common problems in Software Development. The purpose of design patterns is to help structure your code so it will be flexible and resilient when its changed.
There are 23 common design patterns that are being used by programmers around the world. In this chapter I am going to describe the Observer Pattern.