If the previous introductory lecture was a lecture to get a taste of Spring, this lecture allowed me to learn why Spring is necessary and the core technologies of Spring. Also, I thought I could just use new with classes, but through this lecture, I learned for the first time that the principles of object-oriented design are so profound and complicated. I feel like my perspective has been expanded and it was an opportunity to think about object-oriented design again. (I am studying with the book Facts and Misconceptions of Object-Oriented Design that you recommended. Thank you.) Since it was a lecture that I listened to quickly over the course of a week, I only realized the existence of core functions by following the code and thinking, "Oh, there are functions like this too," rather than understanding them perfectly. I think it is still insufficient for practical use. In order to move on to the next step, I plan to develop while practicing directly through the wild developer course that the instructor mentioned. I will continue to work hard in the future. Thank you again to the instructor for giving me a great lecture.