An unspent transaction output available to be used as a future input.
UTXO meaning
UTXO stands for unspent transaction output. Bitcoin wallets calculate spendable value by finding outputs their keys can unlock. A transaction consumes chosen UTXOs completely and creates new outputs; it does not subtract part of an account balance in place.
How it works in Bitcoin
If an input is larger than the payment, the wallet normally sends the remainder to a change output. The set of all currently spendable outputs is called the UTXO set and is central to node validation.
A simple example
Spending a 100,000-sat UTXO to pay 30,000 sats might create a payment output, a change output near 68,000 sats, and a 2,000-sat fee.
Why UTXO matters
Transaction terms matter whenever bitcoin moves. Understanding them reduces mistakes involving fees, confirmation status, change outputs and irreversible destinations.
What people often get wrong
A wallet balance can be split across many UTXOs. That affects transaction size, fees, privacy, and coin-selection behavior even when the displayed total is the same.
Quick checks before using the term
- Is the transaction only broadcast or already confirmed?
- Which outputs and fee are being created?
- Can wallet policy replace or delay it?
Apply these questions to the concrete example above. A precise answer is more useful than repeating the definition without naming the actor, rule or failure path.
Check the primary reference
This entry is written in plain English, but the technical source is available when you need exact protocol detail.
Bitcoin Developer Guide: Transactions ↗