A broad overview of approaches to proof-of-stake blockchain design with Valeria Nikolaenko (a16z crypto Research Partner). Valeria examines both longest-chain and BFT-style consensus protocols, compares them, and examines the variants used in real-world blockchains. She also examines other PoS designs, such as Algorand, Avalanche, and Solana. Valeria also covers leader-election strategies with the use of VRFs and VDFs, and discusses the space of possible attacks. Finally, she examines the consensus layer design of Ethereum.