Transaction
A Bitcoin transaction is a signed message that spends earlier outputs (its inputs) and creates new ones that can be spent later (its outputs).
A payment written down: which earlier coins it spends (its inputs) and where the value goes (its outputs). Once it is in a block it is part of the record for good.
Where is the fee in a transaction?
Nowhere, on its own line. The fee is whatever the inputs hold that the outputs don't pay out. A transaction spending 0.01 BTC and paying out 0.0099 BTC leaves 0.0001 BTC, 10,000 satoshis, for the miner who includes it.
What is change?
Inputs are spent whole, like banknotes. To pay 0.3 BTC from a 0.5 BTC output, a wallet pays 0.3 BTC to the recipient and sends most of the rest back to an address of its own: the change.
When is a transaction final?
Once it is in a block it is confirmed, and every block after that makes it harder to undo. Six confirmations, about an hour, is the usual mark for final.
Sources
- Bitcoin: A Peer-to-Peer Electronic Cash System (the white paper)
- Bitcoin developer guide: transactions
Updated 10 Oct 2026
Related words
Something look wrong? Tell us