At a high level, a transaction is confirmed when it is permanently included in the Bitcoin blockchain. The important conclusion, however, is that there is no absolute notion of “permanent inclusion” and that the community simply uses a reasonably safe policy of considering confirmed transactions when they are “included with very high probability”. The time it takes for this to happen is quite variable. Sometimes a confirmation may take ten minutes and sometimes it may take over two hours, but on average it will take about an hour. Bitcoin’s near-immediate physical settlement opens up a vast design space allowing developers to add cheaper and more convenient payment networks with deferred settlement. The Lightning Network and other second-layer solutions allows for inexpensive, near-instantaneous transfers that periodically settle in the base layer. Not all transactions deserve a final settlement as soon as possible, just like VISA, ACH, and other legacy systems. In these petty cash situations, it is faster to use a higher layer.