what-are-design-patterns-and-why-one-needs-them?

A pattern based designing approach is best suited in devising solutions for problems occurring over and over again.The design patterns are language-independent strategies for solving common object-oriented design problems.

When you design, you should have advanced knowledge of such solutions in order to overcome problems that may occur in your system. GoF, Gang-Of-Four,because of the four authors who wrote, Design Patterns: Elements of Reusable Object-Oriented Software(ISBN 0-201-63361-2) is a software engineering book describing recurring solutions to common problems in software design. The book's authors are Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides. It is language independent approach of designing systems on the based of patterns.