In software engineering, a software design pattern is a general, reusable solution to a commonly occurring problem within a given context in software design. It is not a finished design that can be transformed directly into source or machine code

Design patterns had originally been categorized into 3 sub-classifications based on what kind of problem they solve. Creational patterns provide the capability to create objects based on a required criterion and in a controlled way. Structural patterns are about organizing different classes and objects to form larger structures and provide new functionality. Finally, behavioral patterns are about identifying common communication patterns between objects and realizing these patterns.

1. Creational design patterns (builder, prototype(copy), abstract factory pattern, factory method, Singleton , object pool )
2. Structural design patterns (adapter, facade , flyweight , bridge , decorator, proxy )
3. Behavioral design patterns (strategy, state , command, mediator, chain of responsibility, iterator, template)