What is Reorg?

A reorg (reorganization) refers to an event in a blockchain where a block or a chain of blocks is replaced by an alternative chain. This typically happens when two or more miners or groups of miners simultaneously find valid blocks, leading to a temporary fork in the blockchain. Eventually, one chain becomes longer than the others (usually the one with more accumulated proof-of-work) and is accepted by the network as the main chain, causing the shorter, orphaned chain to be discarded. Transactions included in the discarded blocks may need to be re-included in subsequent blocks to be confirmed. Reorgs can potentially be exploited to double-spend cryptocurrency, although the likelihood of successful exploitation depends on factors like network size and consensus mechanism.