Quote:
Originally Posted by k0nr4d
BTC transfers are not instant, they are only instant when you buy and sell them on an exchange within that exchange. Transfering wallet to wallet takes 10 minutes-ish.
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Actually, transactions propagate throughout the network pretty quick (a matter of seconds). It takes 10 minutes (on average) for a block to get found, and blocks are where the transactions get permanently recorded. It's up to the user to determine the level of risk they are willing to take on when waiting for confirmations. If it's just over a cup of coffee, a 0-conf tx is probably good enough; if it's something more valuable, maybe you want to wait for a confirmation or two; if it's a house, you should definitely wait for 6 or more confirmations. The reason you want to wait for multiple confirmations (or blocks built on top of the history that includes your transaction) is because they represent a certain amount of hard work; work that would have to be re-done by a would-be attacker. It's cost prohibitive to mine an alternate chain of blocks just reverse a single transaction, so it's generally unheard of.