GlossaryAdvanced
Reorg
When a blockchain's recent history is replaced by a different, competing chain of blocks.
A reorganization ("reorg") happens when a network's participants switch from one recent sequence of blocks to a different, competing sequence, effectively replacing a small amount of recent history.
Reorgs of a small number of blocks can occur naturally when two valid blocks are produced nearly simultaneously; a deep reorg affecting many blocks or confirmed transactions would be far more unusual and concerning.
Examples
- A shallow, single-block reorg is a normal, expected occasional occurrence on many networks.
- Waiting for multiple confirmations reduces the practical risk that a transaction is affected by a reorg.