First of all, I listened to the lecture well. It was good to learn about the basics of SpringSecurity. However, I don't think I would recommend this lecture to others. While listening to the lecture, I felt that the instructor only summarized the content he was going to explain when recording the video. In fact, the PDF he uploaded only had a rough outline, and many important contents were explained only verbally. Even the explanations felt more like he was explaining them from memory rather than preparing and organizing them in advance. That's why the explanations were too distracting for the listener, that is, for me. Things that weren't explained at the beginning of the lecture suddenly appeared in the end... Since this lecture was an online lecture, I watched it several times, so I was barely able to understand it, but honestly, it was too difficult. I trusted him because he was famous, so I bought it, but I was very disappointed. I hope that students will think about why they spend a lot of money to buy the lecture.