It was a really informative lecture! The systematic explanation of everything from large-scale system design principles to architectural patterns made the concepts easy to understand, and the analysis of real-world cases helped to concretize abstract concepts. In particular, the parts related to scalability were practical enough to be applied directly in the field. Load balancing, caching strategies, database sharding, and other concepts that I had difficulty understanding were clearly explained, which was very helpful. However, some of the content may be a bit difficult for beginners. I think this lecture is more suitable for those with basic software development experience. Overall, this lecture greatly improved my understanding of system design, and I am now able to make better decisions in practice.