It took a long time to complete up to Part 2. The instructor teaches with sincerity. I hope that the long process will have a good influence. For reference, I used the latest versions of Mac, IntelliJ environment, and API, and I had no problem completing it. Of course, because the environment was different, I had to look it up separately and follow it, but I think that was a good experience. Through the Naph series, I think I was able to learn at least the logic, structure, and principles of the backend. I need to do more application courses. However, it does not explain all the APIs 100%, but explains about 80-90%. This is a lecture recommended for those who want to solidify their basic training. I think that your patience will improve as you build up your skills step by step. If you want a lecture that makes something in a fancy and modern way, please skip it.