GlossaryAdvanced
UTXO
An unspent transaction output — a discrete chunk of cryptocurrency ready to be spent.
UTXO stands for "unspent transaction output." In UTXO-based systems, a wallet's balance isn't a single number in an account; it's the sum of individual, discrete outputs from past transactions that haven't been spent yet.
When someone sends a transaction, it consumes one or more existing UTXOs as inputs and creates new UTXOs as outputs, some of which go to the recipient and some of which may return as change (see Kaavon's "Change Address" glossary definition for where that returned amount actually goes).
Examples
- Bitcoin uses a UTXO model, while many other networks use an account-based model instead.
- Spending a large UTXO to pay a small amount typically generates a change output back to the sender.