Chain Reorganization (Reorg)
Consensus● Common
When nodes switch to a longer valid chain, orphaning previously accepted blocks. Occurs naturally due to near-simultaneous block discovery or maliciously via 51% attacks. Transactions in orphaned blocks return to mempool (if still valid).
Technical Notes
1-block reorgs: occasional, normal. Deep reorgs: rare, concerning. Exchanges wait for confirmations to prevent double-spend via reorg. Checkpoints in old versions prevented very deep reorgs. 'Finality' is probabilistic, not absolute.
Metadata
Visibility: Public
Created:1/3/2026by System