Finality
The point at which a confirmed transaction can no longer be reversed or pushed off the chain.
Finality is the guarantee that a transaction is settled for good. On proof-of-work chains it's probabilistic: each new block on top makes a reversal exponentially harder, which is why exchanges wait for several confirmations.
Some proof-of-stake systems offer faster, near-absolute finality, locking blocks in within a minute or two. Until a transaction is final, there's a small chance a chain reorganization could undo it, so finality matters most for large transfers.
Related terms
Each new block added on top of the one holding your transaction, deepening it and making reversal far harder.
Consensus MechanismThe rules a decentralized network follows to agree on one valid history without trusting any central party.
Proof of Stake (PoS)A consensus method where validators lock up coins as collateral instead of burning electricity to secure the chain.
TransactionA signed instruction that moves value or data on a blockchain, recorded permanently once miners or validators confirm it.