*9 OOP Design Patterns You Must Know* These patterns can be divided into 3 categories: A - Creational Patterns Deal with object creation mechanism to decouple the client code from concrete classes. 1 - Factory Pattern: Centralizes object creation logic and returns different subclasses based on input 2 - Singleton Pattern: Ensures only one instance of a class exists and provides global access to it. 3 - Builder Pattern: Constructs complex objects step-by-step, allowing optional configuration. B - Structural Patterns Help compose classes and objects into larger structures. 1 - Adapter Pattern: Allows incompatible interfaces to work together by translating one interface into another. 2 - Decorator Pattern: Adds new behavior to objects dynamically without altering their original structure. 3 - Proxy Pattern: Acts as a placeholder for accessing another object. C - Behavioral Patterns Focus on communication and interaction between objects. 1 - Strategy Pattern: Allows selecting an algorithm or behavior from a family of interchangeable strategies at runtime. 2 - Observer Pattern: Enables a one-to-many dependency so that when one object changes state, all its dependents are notified. 3 - Command Pattern: An object encapsulates all information needed to perform an action or trigger an event. *React ❤️ for more*