Design PATTERNS are the reusable template solutions that are for solving common problems that occur in software development such as repetitive code, reusable patterns, redundant functions etc. They are similar to customizable blueprints for solving any problem. This concept was first described by Christopher Alexander and was later picked by 4 authors - Erich Gamma, John Vlissides, Ralph Johnson, and Richard Helm - POPULARLY known as the Gang of Four and published in their book Design Patterns: Elements of Reusable Object-Oriented Software in 1994. Design Patterns teaches the DEVELOPERS how to solve commonly recurring problems without spending too much time and effort while developing solutions to them. Due to this, the demand for software developers to KNOW these patterns has grown a lot. 

In this article, we will see the most commonly asked design patterns interview questions for both freshers and experienced professionals.