All terms
How many blocks have been built on top of the one containing your transaction.
When your transaction lands in a block, it has one confirmation. Each block added afterward adds another. More confirmations mean more work would be needed to reverse it, so exchanges wait for a certain number before crediting deposits.
Chains with instant finality, like Algorand or Solana after a short delay, do not work this way. Once finalized, a block cannot be reorganized at all.
Many exchanges wait for 6 Bitcoin confirmations, roughly an hour, before letting you trade a deposit.
That one confirmation means done. One confirmation means your transaction is in the most recent block, and the most recent block is the one most likely to be replaced. Exchanges wait for several for exactly this reason, and so should you for anything large.
Common questions
How many confirmations is enough?
Why do exchanges make me wait so long for a deposit?
Where this comes up on the site
The guides that actually use this word, rather than a list of everything we have written.
Where to go next
More foundations terms
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