A validator vote that a block is valid and belongs on the canonical chain.

The ability of a network to keep a single honest history even if some nodes lie or go offline.

A replicated data structure designed so concurrent changes can converge under specified merge or delivery rules, without coordinating every update.

Token holders elect a smaller set of block producers. Faster, more concentrated, easier to cartelise.

How hard it is to find a valid proof-of-work hash. Networks raise it when blocks arrive too fast.

The rule that retunes mining difficulty so average block time stays near target.

The problem of getting separate processes to agree on values despite failures, subject to explicit communication and fault assumptions.

A fixed number of slots after which validator sets, rewards, or checkpoints update.

A consistency guarantee under which replicas converge once updates stop and propagate, while intermediate reads may disagree.

The point after which a block is treated as irreversible under the protocol's rules.

The rule a node applies to select its preferred chain head when more than one valid branch is available.

The total hashes per second pointed at a proof-of-work network. A security and energy statistic.

Combining work and stake, or BFT plus a longest-chain fallback, to pick different tradeoffs.

An Ethereum proof-of-stake recovery mechanism that increases penalties for inactive validators when the chain fails to finalize for an extended period.

The longest or heaviest-chain rule introduced by Bitcoin. Probabilistic finality, open miner set.

Practical Byzantine Fault Tolerance. A classic voting protocol that finalizes if fewer than one third of voters are dishonest.

Consensus run by a known, permissioned set of validators. Fast, centralized, common on sidechains.

Solana's verifiable delay function that timestamps events so validators can order them with less chatter.

Consensus where validators lock tokens as collateral to propose and attest blocks. Used by Ethereum.

Consensus where miners expend computation to propose blocks. Used by Bitcoin.

The validator chosen to build the next block in a given slot.

A scheduled time window in which one block may be proposed.

A method of replicating a service by having deterministic replicas process the same ordered inputs and produce corresponding states and outputs.

A BFT consensus engine used by Cosmos SDK chains. Instant finality, bonded validators, slashing.

The need for a proof-of-stake node joining or returning after a long absence to obtain a sufficiently recent trusted checkpoint before validating forward.