Inversion of Control

• A design principle: Spring controls object creation and lifecycle.

• Spring has IoC Container, which creates, wires, and manages objects

  ✅ Loose coupling

  ✅ Testability

  ✅ Maintainability

  ✅ Extensibility

// if not using ioc container, u need to control when, how, what is created manually

Main interfaces:

• BeanFactory (basic)
• ApplicationContext (advanced, most used)

What the container does:

1. Scans classes (@Component, @Service, etc.)
2. Creates objects (beans)
3. Resolves dependencies
4. Injects dependencies
5. Manages lifecycle (init, destroy, scopes)