Block Reordering

Definition ∞ The process where a miner or validator changes the sequence of transactions within a block before its inclusion on the blockchain. This action can influence the outcome of pending transactions, potentially allowing for profitable arbitrage or liquidation opportunities. It is a specific form of transaction ordering manipulation. Block reordering can lead to unexpected results for users and undermine confidence in transaction finality.
Context ∞ Block reordering is a critical concern in decentralized finance, often linked to MEV strategies where validators seek to maximize profits. Efforts to mitigate its impact include specialized transaction relay networks and protocol-level adjustments to transaction inclusion rules. The ongoing challenge involves preserving network decentralization while minimizing the ability of block producers to unfairly sequence transactions.