What is a Design Pattern ?

Design Pattern is a re-usable, high quality solution to a given requirement, task or recurring problem. Further, it does not comprise of a complete solution that may be instantly converted to a code component, rather it provides a framework for how to solve a problem.

In 1994, the release of the book Design Patterns, Elements of Reusable Object Oriented Software made design patterns popular.

Because design patterns consist of proven reusable architectural concepts, they are reliable and they speed up software development process.

Design Patterns are in a continious phase of evolution, which means that they keep on getting better & better as they are tested against time, reliability and subjected to continious improvements. Further, design patterns have evolved towards targeting specific domains. For example, windows-based banking applications are usually based on singleton patterns, e-commerce web applications are based on the MVC (Model-View-Controller) pattern