Chain Reorganization

Definition ∞ Chain reorganization, often called a reorg, occurs when a blockchain temporarily diverges, and a shorter chain is replaced by a longer, more canonical one. This event happens when multiple miners or validators simultaneously discover blocks, leading to a temporary fork. The network eventually resolves this by adopting the chain with the most cumulative work or stake. Transactions on the discarded chain become unconfirmed.
Context ∞ News reports on chain reorganizations frequently highlight their impact on transaction finality and network security. While small reorgs are a normal part of blockchain operation, larger or frequent ones can cause concern regarding the integrity of recent transactions. This phenomenon is a critical metric for assessing the stability and decentralization of a blockchain, especially after significant network upgrades or consensus mechanism changes.