It was great to be able to study URL encoding, HTTP request/response message composition in detail again. And especially, the cookie and session parts were explained in great detail, so I was able to grasp the concepts that I had been confused about and vague about. The web architecture analysis part was also really good because the concepts of web server and was were explained clearly. This kind of lecture is free! It's a great lecture because it's not too long but you can learn the key points well!