Proof of Stake in Eth2 represents a large departure from the Proof of Work rules that governed Eth1. Our deep dive into Eth2 begins with an explanation of the theoretical basis of Proof of Stake. This basis allows us to explore in later chapters the Beacon Chain, Eth2's implementation of a Proof of Stake chain based on the ideas described here.

Certain mechanisms described within this chapter can be implemented in a variety of ways. We typically present such mechanisms as "black boxes" and leave their implementation details within Eth2 for our chapters regarding the Beacon Chain. Any simplifications made within this chapter serve only to aid explanation and do not attempt to "hand-wave" important conceptual topics.