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Definition: Bitcoin confirmation


A Bitcoin transaction is considered confirmed when it is included in a new block in the blockchain. Each time another block is appended to the chain, the transaction is confirmed again. To buy an inexpensive item, very often no confirmation is required; however, one confirmation is considered adequate for transactions up to USD $1,000. The more blocks appended, the greater the assurance of an irreversible transaction, and each block takes approximately 10 minutes. Thus for large transactions, six confirmations are generally desired, which can take an hour. For multi-million dollar transactions, dozens of confirmations and hours of waiting may be required. See Bitcoin mining.