You said 'memorize and finish', but I think you could change it to 'understand and finish'! I was worried because I'm not good at memorizing, but you drew it yourself and explained the overall flow well, so I think it's ingrained in my head without me having to memorize it. This is understanding! It feels like the content I knew in parts has been organized well. You didn't go into it in depth, but I think it'll be enough of a milestone for you to delve deeper on your own. Personally, I was touched by the fact that when you try to learn the detailed elements of the OSI 7 layers in the beginning, it feels like you're studying philosophical content like 'friendship, love', so you give up. Just like everyone gets stuck at pointers while learning the C language, I was definitely at a loss there, so I think I ended up not studying the overall flow. And I think I'll always remember the picture you divided into H/W, S/W, kernel, and user mode. Haha. I enjoyed it. Thank you.