After taking Mr. Kiseon's Spring Security class, I gained a deeper understanding of security and also got hints on how to study. In practice, when there was a problem with the security part, there were many cases where I couldn't find the debugging point, but after understanding the Spring Security architecture explained by Mr. Kiseon, it helped me a lot in practice. Also, I felt that development focused on what was working was just a shell, and the part where he taught the operating principles of each by finding the debugging point in the divide and conquer method and combining the principles in the latter part really made me hit my knees. It was the best lecture that allowed me to realize that if I start studying on my own in the future, I should study in this way. I highly recommend it to those who are new to Spring Security👍🏻