This was personally the most difficult lecture, but also the one where I learned the most. In particular, it was my first time dealing with sockets, and it was so much fun. I was able to learn that TCP/IP exists before HTTP, and how to handle TCP/IP with Java, that is, how to utilize sockets. I had been developing while relying only on the sweetness of servlets, which easily handled HTTP, but I became interested in projects that operate on a high-performance basis at the TCP/IP level without HTTP, such as chat or log collection programs. It took me a little long to complete the course, but it was always a good lecture!