Blockchains have no central authority keeping the books, so who decides what the next block will be, and how do they prevent someone from altering the ledger? These are the questions consensus mechanisms answer. The two most common are Proof of Work (PoW), used by Bitcoin, and Proof of Stake (PoS), which Ethereum now uses.

Corresponding coin: $BTC Current price: 82,349.89 (24h +0.77%).

— Proof of Work: Competing with computing power —

Bitcoin uses Proof of Work: miners continuously try to calculate SHA-256 hashes. The first to find a result that meets the difficulty requirement earns the right to record the block and receives the block reward.

Bitcoin produces a block about every 10 minutes on average, and mining difficulty adjusts every 2,016 blocks: when the network’s total computing power rises, difficulty increases accordingly, bringing block times back to around 10 minutes.

— Proof of Stake: Putting Up Stake as Collateral —

In September 2022, Ethereum switched from Proof of Work to Proof of Stake through “The Merge.” Running a validator requires staking at least 32 ETH. Validators take turns proposing and attesting to blocks according to the rules.

Under Ethereum’s Proof of Stake, each slot lasts 12 seconds, and at most one block can be produced per slot. Validators who misbehave have some of their stake slashed, while those who stay offline for a long time also lose some of their balance.

— What Keeps It Secure? —

Proof of Work relies on real investments in computing power and electricity: rewriting the historical record would require controlling most of the network’s computing power, at an enormous cost.

Proof of Stake uses staked assets as collateral: attacking the network requires controlling a large amount of stake, and if the misconduct is discovered, that stake is slashed. Both make the cost of misbehaving far greater than the potential gain; they just put different things at stake.

— Don’t Compare Consensus Mechanisms in Isolation —

When discussing which blockchain is more secure, the consensus mechanism is only one part of the picture. How widely nodes and validators are distributed, the quality of the client software, and how the community responds when things go wrong are just as important.

— In Summary —

Once you understand PoW and PoS, terms like “hash power,” “staking,” and “slashing” will make more sense in the context of the system as a whole. It’s okay to take things slowly; staying in the game matters more than how much you make on any one occasion.

Type 1 if you learned something. If anything’s unclear, keep asking in the comments.