Nakamoto consensus is the consensus approach introduced with Bitcoin. Miners compete to produce proof-of-work blocks, while nodes independently check blocks and transactions against the rules they enforce. When valid branches compete, the chain with the greatest accumulated proof of work is preferred, not simply the one supported by the most node identities.
Resolving temporary disagreement
Two miners can find blocks close together, causing nodes to temporarily see different chain tips. As additional work extends one branch, nodes can reorganize their local history to follow the preferred valid chain. Transactions from a displaced block may need inclusion elsewhere.
“Longest chain” is common shorthand, but accumulated work is the more precise criterion; block count alone can be misleading when difficulty differs.
Confidence grows under assumptions
Further confirmations generally make replacing a transaction’s history harder when honest mining power dominates and network communication remains adequate. This is probabilistic settlement, rather than an absolute promise that a confirmed transaction can never be reorganized.
An attacker with enough mining power may censor transactions or attempt to replace their own payments. Mining power does not by itself authorize forged signatures or arbitrary coin creation that validating nodes reject.
The approach ties influence to computational work and economic incentives. Its practical security also depends on mining concentration, connectivity, and implementation quality.