I want to learn and use the Spring Boot technology that I am currently using right now, but I was really impressed that it kept going back to 20 years ago and explaining the technologies used at that time, and after listening to it all, I was able to roughly guess the internal logic of how the technologies currently used work. In particular, when connecting to a database, I just thoughtlessly entered the url, name, and pass in application.properties and connected it, but after listening to the lecture, I realized that the old method was too cumbersome, and when I saw the process of eliminating those points, I understood how the current method was automated.