There were some difficult parts in understanding TypeScript accurately, but by properly listening to the lectures, I was able to understand the core concepts well. The understanding of supertypes and subtypes, as well as utility types, was particularly helpful. In fact, utility types felt like the most difficult part - to the point where I wondered if studying types was necessary just to understand utility types. But after understanding them, I realized there are no types as convenient as these... This was a TypeScript lecture that was truly very helpful. Thank you for creating such a great lecture.