This section explores the vital role of consensus mechanisms in blockchain technology. Consensus mechanisms help blockchains agree on transaction validity and ledger updates. Two major mechanisms, "proof of work" and "proof of stake," are explained. "Proof of work," used by Bitcoin, involves solving complex math problems to mine blocks and earn crypto rewards. "Proof of stake," used by Ethereum, selects validators based on staked crypto assets. Understanding these mechanisms is key to comprehending how blockchain networks validate transactions.