Exploring blockchain #1

While reading the cloned Bitcoin C++ code in the Dogecoin repo, I realized I didn’t understand blockchain enough. A while back YT recommended MIT’s blockchain OpenCourse, and while seeing the “testnet” and “ipc” in the C++ file, the thought of that OpenCourse popped in my head. I searched for it, and I pulled up the course’s reading material. From this I searched for and started reading the most substantive-looking doc I could find. While reading, I realized I didn’t know as much as I thought I did about what even a “block” is and how “consensus” is achieved, i.e. what is proof of work vs. proof of stake vs. round-robin?