Blockchain Finality Rules

Definition ∞ Blockchain finality rules specify when a transaction on a blockchain is considered irreversible and permanently recorded. These rules vary significantly across different blockchain protocols, depending on their consensus mechanisms. In Proof-of-Work systems, finality is probabilistic, increasing with the number of subsequent blocks. Proof-of-Stake systems often achieve deterministic or economic finality, where transactions become irreversible after a certain threshold of validator agreement. Understanding these rules is essential for assessing transaction security and network reliability.
Context ∞ Debates surrounding blockchain finality rules are prominent in discussions about cross-chain interoperability and the security guarantees of various layer-one and layer-two solutions. News regarding protocol upgrades or security incidents often highlights the specific finality properties of a given blockchain. The ongoing push for faster and more certain transaction finality drives innovation in consensus algorithm design.