Starting with the launch of the second blockchain, connecting any blockchain to any other blockchain without additional trust assumptions has been an elusive dream. Ten years later, application developers must still settle for some version of this.

This is a sequel to Notes on Paxos post.
Similarly, the primarily goal here is for me to understand why the BFT consensus algorithm works in detail.
This might, or might not be useful for other people!
The Paxos article is a prerequisite, best to read that…