I listened to it like a charm. In order to listen to the second part more actively, I wrote down my questions and searched for them. While searching for questions about the cookie and session section, I gained new knowledge such as how SpringSecurity solves problems, and while searching for questions about the file upload section, I learned about Amazon S3 and image processing. There was even a separate class called AmazonS3. I had a hard time because of questions that arose while listening to the API lecture, and somehow I ended up flowing into Samcheonpo and going to DDD and buying a few books. The more I listened, the more questions I had, but I felt that I could solve them if I studied them, so it was good. The lecture was really informative, thank you. I have been listening to the Spring introductory lecture, and in the 'Next' section, you always say that you are a scholar, but somehow... I think it is better to go with a wild developer style, so I am going to listen to the DB and JPA lectures while creating a community site or something. Fighting!