I can confidently say that this is the best lecture among all the lectures I paid for at Inflearn. The original curriculum structure that was created by racking my brain without copying from books, the essence of each lecture, no rambling, clean comments and sentences, appropriate speed and clear speech, and the concrete practical method of testing to draw the big picture of design, and then draw the test under the design again. You can see how much the instructor has thought, repeated, improved, and developed. He has amazingly incorporated all of that into the lecture. I have only taken one or two lectures at Inflearn, but I have never seen A/S as refined as this lecture. After filming, videos are not as easy to edit as text, and due to the nature of the lecture, there must be a strong desire to always show something beautiful and without a single mistake, so I have refined those parts without any additions or subtractions. When the instructor makes a mistake or says, "I wish I had done this," there is a section where the screen turns gray and only the voice appears. When this part comes up, I can check if I'm listening with my wits about me, compare it to my thoughts, and think that the instructor also has such concerns. Anyway, these A/S videos are like a well-written script, and they serve as great educational tools. I bought the test, but the design came with it. But the design was more expensive than the test. I'm writing a review for the first time because I'm mad that there are only 54 reviews for this crazy great lecture. The content, voice, audio, video, and length... everything was cohesively put together, so it was like looking at a beautiful design. Personally, I liked Instructor Kim Woo-geun's lecture much better than the named lecture with +9,999 students.