In a word, it was a "worthwhile lecture". Of course, there are errors and parts that make you wonder what's going on. However, if you listen to the lecture several times, you can understand it well enough. You can learn React, Spring, and restful API. I recommend studying with the book. Since the book is a printed version, the instructor will update the version to the latest version while lecturing if there are any parts that are not compatible. If there are parts that you miss or can't organize while listening to the lecture, you can read the book to organize them. I think it was easier to understand by studying while comparing the book and the lecture. In particular, in the testing part, the lecture clearly explained how much coding and testing to do, and the meaning of testing was clearly explained. The lecture time is quite long, so patience and perseverance are required. It would have been better if there was a final distribution lecture, but I will try my best to finish the last part by looking at the book. Thank you for the good lecture.