Proof-of-Work vs Proof-of-Stake
Two different answers to the same question: how do strangers online agree on what's true?
> Proof-of-Work
Miners compete to find a nonce that produces a block hash below a target threshold. Finding it requires trillions of guesses per second, which requires electricity. The security assumption: an attacker would need to out-spend the honest majority in real-world energy costs.
> Proof-of-Stake
Validators lock up (stake) the network's native token as collateral. The protocol picks one to propose each block. Misbehavior — proposing invalid blocks, going offline — causes the stake to be 'slashed'. Security comes from capital at risk instead of energy spent.
> Trade-offs
PoW is battle-tested and physically grounded but energy-intensive. PoS is far more efficient and enables features like fast finality, but centralization pressures on staking pools and complexity in the protocol are real concerns. Bitcoin uses PoW; Ethereum switched to PoS in 2022.