It is definitely the number one thing I spent money on this year that I don't regret. I haven't taken many courses on Inflearn, but the content they provide is so valuable for the price. I wanted to study Spring Security, but since most books on the market are based on version 5, I chose this course, which is based on version 6. I've always liked studying the details of the principles, and that matched the instructor's style, so it was a very satisfying course for me. I was able to get an overview of the theoretical aspects of security, which has a high entry barrier. Of course, it's impossible to master all the content at once, and I think I'll be referring to it often as I develop in the future. Apart from security, the instructor uses the debugging function very well during the course, and I had hardly used the debugging function before. I used to check almost everything with print statements, but after seeing the instructor's debugging, I developed a habit of finding code errors through debugging in Spring Boot projects as well as security. I think this is also a great achievement. Thank you for the great course.