Definition
Finality is a consensus-level property of a blockchain or distributed ledger that characterizes the point at which a confirmed state transition, such as a block or transaction, is considered irreversible under the protocol’s security assumptions. Once finality is reached, the probability of that state being reverted, reorganized, or superseded is treated as negligibly small, given the specified adversarial and fault tolerance model.
In Simple Terms
Finality is the moment when a blockchain decision is treated as permanent. After this point, the network regards the included transactions and blocks as effectively impossible to change or undo, assuming the system’s security conditions hold.
Context and Usage
Finality is discussed in the context of consensus design, security guarantees, and settlement assurances for blockchain systems. It is used to distinguish between tentative confirmations and protocol-recognized permanence of ledger entries. The term appears frequently in analyses of economic security, adversarial models, and the behavior of validators or nodes under different consensus mechanisms, especially when evaluating settlement risk and rollback likelihood.