How long does it take for a Bitcoin transaction to be confirmed?
Frequently in popular descriptions of Bitcoin and in the user interfaces of wallet software, a distinction is made between “confirmed” and “unconfirmed” transactions. What is the difference? At a high level, a transaction is only confirmed when it is permanently included in the Bitcoin blockchain. The blockchain is a ledger of all transactions in the history of Bitcoin. It is append-only, meaning new data can be added to the end of the ledger, but data can never be removed once included. This ledger is necessary to prevent double-spending, which is a key technical challenge in designing any cryptocurrency - of which we'll talk more in the following articles. How Bitcoins are Transferred Recall that if Alice “owns” some quantity of bitcoins, this really means she knows one or more cryptographic keys which have been designated as the controller of those coins in a transaction on the ledger which transferred the coins to Alice. In order to transfer the coins to another entity,