Hello. This is Zero. Thank you for the first review of the revised edition. Technical books are difficult. The first reason is that I don't know the knowledge, so it takes time to understand that knowledge, and the second reason is that it takes time until the knowledge I read in the previous chapter is used as experience to understand the next chapter. Finally, technical books cannot be read in a short time, and since human memory has a forgetting curve, short-term memory disappears quickly, so knowledge I read a long time ago feels unfamiliar. Video lectures are the same. However, if you watch the lecture from beginning to end without giving up, the situation will be different. Through the table of contents, I have the opportunity to find the technology I actually need. If you need IoC knowledge used during development, select "Implement DI and IoC that can reuse service logic" in the table of contents and look again, and if you need a thread-safe coding method in a multi-threaded environment, "Use the log function in a multi-threaded environment." You can choose and apply it. If you still don't understand, it's okay to ask the person who created the lecture. (Questions are very welcome.) In other words, you don't need to read the technical book repeatedly or organize the whole thing in your head. Since you've read the whole thing once, I hope you can choose only what you need and gain knowledge and experience from now on. I'm really grateful that you watched my lecture to the end. Although it's a shame that it's only 3 points, I'd like to give you a small gift (gift card) if you listened to the whole lecture and wrote your first review, I'll send it to you if you reply to the email address in the lecture introduction.