What is consensus?

The mechanism a blockchain uses to agree on which transactions are valid without a central authority.

proof of work and proof of stake are the two dominant designs. The choice determines how the network is secured, who gets to add blocks, and how new coins are issued, which makes it the single most consequential design decision a chain makes.

The thing worth understanding is what consensus is actually solving. Thousands of computers that cannot trust each other, connected by an unreliable network, must agree on one ordering of transactions. Ordering is the hard part, because it is what prevents the same coin being spent twice.

How it works

Every consensus design answers three questions: who may propose the next block, how the network chooses between competing proposals, and what it costs to lie.

Proof-of-work answers with computation. Miners race to find a hash below a target, the winner proposes the block, and the network follows the branch with the most accumulated work. Lying costs electricity and hardware, which are external to the system.

Proof-of-stake answers with capital. Validators lock the chain's own asset, are selected to propose, and vote to attest to what they see. Lying costs the stake itself through slashing, which is internal to the system.

Other designs exist and generally trade decentralization for speed. Delegated schemes elect a small validator set, and permissioned chains simply name one. Fewer participants means faster agreement and a smaller group to compromise or compel.

Consensus does not decide what the rules are. It decides which blocks follow them. Changing the rules themselves is a fork, which is a social and governance process rather than a consensus one.

Example

Illustrative. Two miners find a valid block at nearly the same second, so half the network sees one and half the other. Both blocks are legitimate. The tie breaks when the next block appears: whichever branch it extends now has more accumulated work, and nodes on the other branch switch to it. The losing block's transactions return to the mempool and are usually included shortly after. Nobody voted and no authority ruled, which is the point.

Why it matters when you buy

Consensus design determines how long you wait before a deposit is safe to credit, what a transaction costs, and how the asset's supply grows. A proof-of-stake chain also lets you earn a protocol yield by staking, which proof-of-work does not offer. The chain pages compare networks, and the yield pages show where staking is available by venue.

Related terms

proof of work — security bought with computation; proof of stake — security bought with staked capital; validator — who participates under proof-of-stake; finality — when agreement becomes irreversible; fork — changing the rules rather than applying them.

Questions

Which consensus mechanism is better?

They optimize differently. Proof-of-work anchors security in an external cost, and proof-of-stake makes attacks slashable and uses far less energy. RampAtlas does not rank them, because the answer depends on what you are weighing.

Does consensus prevent bad transactions?

It prevents invalid ones, meaning transactions that break the protocol's rules. It has nothing to say about a valid transaction sending funds to a scammer, which is why irreversibility cuts both ways.

Why do different chains need different confirmation counts?

Because the cost of reversing history differs. A chain with little hash rate or little staked value is cheaper to attack, so exchanges wait for more blocks before treating a deposit as settled.