Block Reorganization

Definition ∞ Block reorganization describes a temporary event in a blockchain where a previously accepted block becomes detached from the longest chain, replaced by an alternative sequence of blocks. This occurs when network nodes receive and validate a new, longer chain of blocks that supersedes their current version of the chain. A reorganization indicates that the network has reached a new consensus on the canonical history of transactions. Such events can cause previously confirmed transactions to revert or change their block inclusion.
Context ∞ Block reorganizations are a normal part of how decentralized blockchain networks achieve consensus, especially in Proof-of-Work systems. While usually minor and quickly resolved, larger reorganizations can attract news attention due to their potential impact on transaction finality and network security. Developers continually work on protocol improvements to minimize the frequency and depth of these events, aiming to bolster transaction reliability for users and applications.