The metadata that tell Spring how to manage classes, methods, or fields. Let Spring to:

• Auto detect beans
• Manage dependencies
• Configure behavior at runtime

// replace manual XML configuration: code cleaner & maintainable.

@SpringBootApplication

• Mark the main config class of the app.
• Saves boilerplate
• Auto-configuration power
• Convention over configuration

@Configuration

• Marks the class as a source of bean definitions for the application context.

@EnableAutoConfiguration

• Tells Spring Boot to auto add beans based on classpath settings, other beans, and property settings
  • Without this, need to config all @Bean manually.
• If have spring-boot-starter-web on classpath: auto-configures Tomcat, DispatcherServlet, and Jackson JSON converter.
• How it work:
  • Checks classpath (dependencies)
  • Checks application.yml
  • Applies @Conditional rules

@ComponentScan