Confirmation is a state where a process or transaction has been encoded or written onto the immutable ledger called the blockchain.  Confirmation first requires that miners validate a transaction by including it in the next or current block.  But inclusion of the transaction in a block does not necessarily mean it is confirmed because the block  has to be a certain “depth”  or buried beneath enough blocks for it to be considered confirmed.

Transactions in Bitcoin are usually considered confirmed if they are at least 6 blocks deep, this means that at an average blocktime of 10 minutes per block, a transaction is considered confirmed in 60 minutes or an hour.  Other services like exchanges may have faster confirmation times if they reduce the number of confirmations required before a transaction is considered spendable.


Think of confirmation as a document that requires multiple signatures for validation, where the more signatures that sign the document the more secure it is.



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