Transactions

Why do I have to wait 10 minutes?

Receiving a payment is almost instant with Bitcoin. However, there is a 10 minutes delay on average before the network begins to confirm your transaction by including it in a block and before you can spend the bitcoins you receive. A confirmation means that there is a consensus on the network that the bitcoins you received haven't been sent to anyone else and are considered your property. Once your transaction has been included in one block, it will continue to be buried under every block after it, which will exponentially consolidate this consensus and decrease the risk of a reversed transaction. Every user is free to determine at what point they consider a transaction confirmed, but 6 confirmations is often considered to be as safe as waiting 6 months on a credit card transaction.

How much will the transaction fee be?

Most transactions can be processed without fees, but users are encouraged to pay a small voluntary fee for faster confirmation of their transactions and to remunerate miners. When fees are required, they generally don't exceed a few pennies in value. Your Bitcoin client will usually try to estimate an appropriate fee when required.

Transaction fees are used as a protection against users sending transactions to overload the network. The precise manner in which fees work is still being developed and will change over time. Because the fee is not related to the amount of bitcoins being sent, it may seem extremely low (0.0005 BTC for a 1,000 BTC transfer) or unfairly high (0.004 BTC for a 0.02 BTC payment). The fee is defined by attributes such as data in transaction and transaction recurrence. For example, if you are receiving a large number of tiny amounts, then fees for sending will be higher. Such payments are comparable to paying a restaurant bill using only pennies. Spending small fractions of your bitcoins rapidly may also require a fee. If your activity follows the pattern of conventional transactions, the fees should remain very low.

What if I receive a bitcoin when my computer is powered off?

This works fine. The bitcoins will appear next time you start your wallet application. Bitcoins are not actually received by the software on your computer, they are appended to a public ledger that is shared between all the devices on the network. If you are sent bitcoins when your wallet client program is not running and you later launch it, it will download blocks and catch up with any transactions it did not already know about, and the bitcoins will eventually appear as if they were just received in real time. Your wallet is only needed when you wish to spend bitcoins.

What does "synchronizing" mean and why does it take so long?

Long synchronization time is only required with full node clients like Bitcoin Core. Technically speaking, synchronizing is the process of downloading and verifying all previous Bitcoin transactions on the network. For some Bitcoin clients to calculate the spendable balance of your Bitcoin wallet and make new transactions, it needs to be aware of all previous transactions. This step can be resource intensive and requires sufficient bandwidth and storage to accommodate the full size of the block chain. For Bitcoin to remain secure, enough people should keep using full node clients because they perform the task of validating and relaying transactions.