What exactly does `@SpringBootApplication` bundle together?

It's a meta-annotation combining three: `@Configuration` (this class can define beans), `@EnableAutoConfiguration` (turn on the classpath-conditional auto-config scanning), and `@ComponentScan` (scan this package and sub-packages for `@Component`/`@Service`/`@Repository`/`@Controller` classes). Understanding this matters because moving your main class to a different package can silently break component scanning for classes outside its scan radius.