Can you list the main design patterns used in object-oriented programming?

The main design patterns in object-oriented programming are divided into three groups:

1. Creational — responsible for object creation:

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

2. Structural — define ways to compose classes and objects:

   • Adapter
   • Decorator
   • Facade
   • Composite
   • Proxy
   • Bridge
   • Flyweight

3. Behavioral — responsible for interactions between objects:

   • Observer
   • Strategy
   • Command
   • Iterator
   • State
   • Template Method
   • Mediator
   • Chain of Responsibility

These patterns help write flexible, extendable, and maintainable code.