UTXO
A UTXO is an unspent transaction output that represents a discrete amount of cryptocurrency available to be used as an input in a future transaction.
✦ Key Insight
UTXOs affect transaction size, privacy, fees, coin control and how Bitcoin wallets construct payments.
✕ Common Misconceptions
A wallet balance is not necessarily one spendable object. Using many small UTXOs can make a transaction larger and more expensive.
Detailed Explanation
In Practice
Dig Deeper
Transaction
A blockchain transaction is a signed or authorized instruction that changes blockchain state or transfers value when accepted by the network.
Dust
Dust is a crypto amount so small that spending it may be uneconomical because transaction fees can approach or exceed its value.
Coin control
Coin control is a Bitcoin wallet feature that lets users choose which specific UTXOs will be spent in a transaction.
sat/vB
sat/vB means satoshis per virtual byte and is a common unit for expressing the fee rate of a Bitcoin transaction.
Change output
A change output is the portion of selected UTXO value returned to the sender when the inputs exceed the amount being paid plus transaction fees.