Fundamentals

Confirmation

Each block mined on top of the block containing a transaction adds one confirmation, making reversal exponentially harder.

A transaction in the latest block has one confirmation; each subsequent block adds another. Reversing a transaction with n confirmations requires secretly re-mining n+1 blocks faster than the honest network — practically impossible beyond a handful of confirmations on a large chain.

Exchanges typically credit Bitcoin deposits after 2–6 confirmations. For miners, pool payouts and freshly mined coinbase rewards follow stricter maturity rules (100 blocks on Bitcoin) before the funds are spendable.

Related Terms

Orphan Block (Stale Block)
51% Attack

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