This lecture covers permissionless consensus and multi-valued history consensus in Bitcoin and distributed ledger technology, explaining the concepts of information-based money, ledger, transactions, and public keys. The instructor, Bryan Ford, discusses the challenges and mechanisms of permissioned consensus, including Multi-Paxos, Raft, and PBFT. The lecture also delves into the concept of asynchronous pacing and consensus, introducing the Threshold Logical Clock (TLC) and 'Que Sera Consensus' (QSC) as alternative consensus mechanisms.