Design patterns are reusable solutions to common software design problems. In Java, they are categorized broadly into three main types:

1. Creational Design Patterns
   Focus: Object creation mechanisms to create objects in a way that is suitable for the situation.

   • Help make the system independent of how objects are created, composed, and represented.
   • Key idea: Control object creation to ensure flexibility and reuse.

   Examples:

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

2. Structural Design Patterns
   Focus: Class and object composition to form larger structures.

   • Help ensure that different parts of a system work together in a flexible and efficient way.
   • Key idea: Simplify relationships between objects or combine them for new functionality.

   Examples:

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

3. Behavioral Design Patterns
   Focus: Interaction and communication between objects.

   • Help define how objects interact, how responsibilities are distributed, and how workflows are controlled.
   • Key idea: Streamline complex communication between objects.

   Examples:

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

Quick Analogy for Understanding Types

1. Creational Patterns: Think of building a house. You decide how to construct it: blueprint (Prototype), modular pieces (Builder), or hiring a factory (Factory Method).
2. Structural Patterns: Consider how you connect rooms: walls (Adapter), open spaces (Bridge), or fancy decorations (Decorator).
3. Behavioral Patterns: It’s about how people in the house interact: assigning tasks (Command), following workflows (Template Method), or broadcasting news (Observer).