Reorg reality

Chain reorganizations ("reorgs") are a designed-in part of Nakamoto consensus, not a failure mode. When two miners find blocks near-simultaneously, the network briefly holds competing tips until one branch accumulates more work; nodes then discard the losing block(s). One-block reorgs occur naturally a handful of times per year on modern Bitcoin; deeper natural reorgs are increasingly rare (a two-block reorg at height 941,880 in March 2026 was notable enough to make industry news). Transactions in orphaned blocks return to the mempool and are typically re-mined promptly.

Nuance: Deep reorgs are the attack scenario (see fifty-one-percent-attack); shallow reorgs are network physics. The 100-block coinbase maturity rule exists specifically to insulate spending of new coins from reorg risk (see coinbase-maturity).

Common misstatements:

• "A reorg means Bitcoin was hacked." — Shallow reorgs are routine consequences of propagation latency.
• "Orphaned transactions are lost." — Unless they conflict with a transaction in the winning branch, they re-enter the mempool and confirm again.
• "The longest chain wins." — Precisely, the chain with the most accumulated proof-of-work wins; "longest" is shorthand that fails in edge cases.