There are some comments that the lecture font is a little small, and it is definitely small. It is a lecture that I feel is very difficult to view on an app. However, if you have a monitor, I felt it was a really good lecture, and since I learned through a monitor, I didn't have any major inconveniences. It is a lecture for beginners, and it does not provide a perfect service, but I think it is the best lecture to experience and learn what a WebSocket is.