# Low Level Design
All Low Level Design notes →1 — Introduction to Design Patterns
What a design pattern actually is, why the Gang-of-Four catalog still matters in interviews, and how to recognize which category a problem is asking for.
2 — Creational Patterns
The five creational patterns — Singleton, Factory Method, Abstract Factory, Builder, and Prototype — for controlling how and when objects get created.
3 — Structural Patterns
The seven structural patterns — Adapter, Bridge, Composite, Decorator, Facade, Flyweight, and Proxy — for composing classes and objects into larger structures.
4 — Behavioral Patterns
The eleven behavioral patterns — from Strategy and Observer through Visitor and Interpreter — for managing communication and responsibility between objects.
5 — Pattern Selection Guide
A decision framework for picking the right pattern under interview pressure — when to reach for one, when it's overkill, and the trade-offs behind each choice.
# Object Oriented Programming
All Object Oriented Programming notes →1 — Creational Patterns
Catalogs Singleton, Factory Method, Abstract Factory, Builder, and Prototype — the patterns that control how objects get created.
2 — Structural Patterns
Catalogs Adapter, Bridge, Composite, Decorator, Facade, Flyweight, and Proxy — the patterns that compose objects into larger structures.
3 — Behavioral Patterns
Catalogs Observer, Strategy, State, Command, Chain of Responsibility, Visitor, Iterator, Mediator, Template Method, Interpreter, and Memento — the patterns that govern how objects communicate and share responsibility.