Overview
Finality is the point at which a blockchain transaction or block is considered irreversible and cannot be reverted. It determines how long users must wait before trusting a settlement. Different consensus mechanisms provide different finality guarantees.
How It Works
Proof-of-work chains offer probabilistic finality: each new block on top of a transaction makes its reversal harder, but never impossible. Proof-of-stake chains often provide economic finality, where validators are penalized for attempting to revert finalized blocks. The mechanism defines the security of settlement.
Why It Matters
Finality affects how quickly users can safely treat a transaction as settled. Faster finality improves the experience for payments and trading, while weaker finality increases the risk of reorgs. It is a key consideration when choosing a chain.
Related Concepts
Finality connects to Probabilistic Finality, Fork Choice Rules, and Checkpoints. It is a core property of Consensus mechanisms and Layer 2 settlement.