# UTXO

URL: https://blockspace.wiki/glossary/utxo/

An unspent transaction output. A Bitcoin wallet's balance is the sum of the UTXOs its private keys control, and the UTXO set is every unspent output on the chain. Ordinal theory tracks individual sats as they move from a transaction's inputs to its outputs, first in, first out.

Sources:

- Bitcoin Wiki: UTXO · https://en.bitcoin.it/wiki/UTXO
- The ordinals handbook: overview · https://docs.ordinals.com/overview.html

Updated: 2026-10-21