-> are optimized reusable solutions to the programming problems that we encounter every day.
-> Generic solutions to the common problems which are encountered in object oriented software design.

Creational
-> Creational patterns provide instantiation mechanisms, making it easier to create objects in a way that suits the situation.

• Singleton
• Factory Method
• Abstract Factory
• Builder
• Prototype

Structural
-> Structural patterns generally deal with relationships between entities, making it easier for these entities to work together.

• Adaptor
• Façade
• Proxy
• Bridge
• Composite
• Decorator
• Flyweight

Behavioral
-> Behavioral patterns are used in communications between entities and make it easier and more flexible for these entities to communicate.

• Observer
• Command