Status: OUT
The Gang of Four catalog defines 23 design patterns organized into three categories: 5 Creational (Abstract Factory, Builder, Factory Method, Prototype, Singleton), 7 Structural (Adapter, Bridge, Composite, Decorator, Facade, Flyweight, Proxy), and 11 Behavioral (Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, State, Strategy, Template Method, Visitor).