What is the role of the @Controller annotation in the application structure?

The @Controller annotation in Java (most commonly in the Spring Framework) designates a class as a controller in the MVC (Model-View-Controller) architecture. This means that the class is responsible for handling HTTP requests, receiving data from the user, invoking business logic, and returning a response (such as a web page or JSON data).

Example:

@Controller
public class UserController {
    @GetMapping("/users")
    public String listUsers(Model model) {
        model.addAttribute("users", userService.getAllUsers());
        return "userList"; // view name
    }
}

Here, @Controller allows Spring to detect this class and register it as a request handler.