What is the purpose of annotations @Component, @Repository, and @Service in Spring, and how do they differ?

Annotations @Component, @Repository, and @Service in Spring are used for automatic detection and registration of components in the application context (dependency injection).

• @Component — a basic annotation for any Spring component. Marks a class as a Spring bean.
• @Repository — a specialized component intended for the data access layer. Besides registering as a bean, Spring can automatically handle database exceptions and translate them into unified Spring exceptions.
• @Service — an annotation for the service layer, indicating business logic. Mainly used for semantic separation of code and can be used for additional aspects, such as transactions.

Example:

@Repository
public class UserRepository { ... }

@Service
public class UserService { ... }

@Component
public class UtilityComponent { ... }