I think I learned about the working principles of Spring Security and how to customize it over the course of a month. When I was working on a Spring Framework project without knowing about security, I implemented HandlerInterceptor to handle authentication/authorization using the user information and authority (Integer value) contained in the Session. I learned about security as well, and I plan to change the authentication/authorization method of the existing toy project. Thank you for the great lecture and knowledge sharing. I think I should watch this lecture again to review after taking the REST API lecture.