This is an incredible lecture that can follow the major flow of 20 years of Java backend history in 15 hours. As soon as I saw the lecture material, I could feel the effort that Younghan put into this lecture despite his busy daily life. If he later condenses the lectures and publishes them as a book, I think it will become the bible of the Spring framework following Toby's Spring. I am happy that I can still take this quality lecture repeatedly. Thank you for always opening up good lectures.