With this lecture, I have already taken a total of 9 of Younghan's lectures. I hope that developers in the field also take Younghan's lectures. You may think that you can just use AOP by looking at the lecture curriculum, but I think that there are few developers who know how AOP came to be in its current form, what process it went through, and the exact original explanation of AOP. Including me. The reason is that Younghan's lectures do not simply focus on how to implement, but rather on why it is implemented that way. The lecture method of writing the initial version code, explaining the limitations, and explaining the process of upgrading while overcoming the limitations seems to help understanding a lot. Even if you know the content from the curriculum, if you listen to Younghan's lecture, you will definitely see a new side. I recommend it to those with more experience. This is not just a lecture review for "Spring Core Principles", but a lecture review for all lectures in general.