Design patterns are reusable, general solutions to commonly occurring problems in software design. The main categories are Creational, Structural, and Behavioral patterns.
Design patterns are typical solutions to common problems in software design. They are like pre-made blueprints that you can customize to solve a recurring design problem in your code. They are not finished code but templates or descriptions of how to solve a problem that can be used in many different situations.
Creational Patterns: These provide object creation mechanisms that increase flexibility and reuse of existing code. Examples include Singleton, Factory, Abstract Factory, Builder, and Prototype.
Structural Patterns: These explain how to assemble objects and classes into larger structures while keeping these structures flexible and efficient. Examples include Adapter, Bridge, Composite, Decorator, Facade, Flyweight, and Proxy.
Behavioral Patterns: These are concerned with algorithms and the assignment of responsibilities between objects. They describe how objects communicate and interact. Examples include Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, State, Strategy, Template Method, and Visitor.