Blockchain glossary
Blocks, confirmations and consensus: the moving parts behind an on-chain transaction. Pick up the words and see how the network fits together.
Block
A batch of blockchain data that is accepted as one step in the network’s history.
Block explorer
An interface that indexes blockchain data for inspecting blocks, accounts and transactions.
Block header
A compact set of block fields used to identify the block and check important validity requirements.
Block height
A block’s numbered position in a chain, counted from the first block.
Block time
The interval between successive blocks, or a protocol's intended interval when quoted as a network statistic.
Blockchain
A shared ledger whose blocks are linked by cryptographic hashes.
Chain reorganization
A change to the accepted chain that replaces previously accepted blocks with another valid branch.
Confirmation
Inclusion of a transaction in a block, with later blocks adding confidence that it will remain accepted.
Consensus
Agreement about which valid blockchain history and state the network accepts.
Consensus rules
The protocol rules that determine whether blockchain transactions and blocks are valid.
Double spending
An attempt to spend the same digital funds in two conflicting payments.
Faucet
A service that distributes small amounts of test-network assets for development.
Finality
The degree of assurance that an accepted transaction or block will not be replaced.
Fork choice
The rule a node uses to select its preferred chain when multiple valid branches exist.
Full node
Software that independently checks blockchain transactions and blocks against the network’s rules.
Genesis block
The first block from which a blockchain’s history begins.
Hard fork
A rule change that can make blocks valid under the new rules but invalid under the old ones.
Light client
A client that checks selected blockchain information using compact proofs and protocol-specific assumptions.
Mainnet
A blockchain's production network, where its assets and transactions have their normal economic role.
Mempool
A node’s local collection of valid pending transactions waiting for block inclusion.
Node
A computer or software instance participating in a blockchain network.
Peer-to-peer
A network design where participants exchange information directly with other participants.
Proof of stake
A consensus approach that uses committed assets to help select validators and hold them accountable.
Proof of work
A mechanism that requires computational work to qualify a candidate block for acceptance.
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