Unspent Transaction Output — the fundamental unit of Bitcoin accounting, representing a discrete chunk of Bitcoin that has been received but not yet spent.
Bitcoin does not use accounts with running balances the way a bank does. Instead, it uses UTXOs: when you receive Bitcoin, the transaction creates a UTXO that is locked to your address. Your "balance" is simply the sum of all UTXOs locked to your address(es). When you send Bitcoin, you "spend" specific UTXOs as inputs to a new transaction, which creates new UTXOs as outputs — some going to the recipient, some returning to you as change.
UTXOs are the foundation of on-chain analysis. Because each UTXO retains its creation timestamp (the block in which it was created), analysts can determine how long any piece of Bitcoin has been dormant. A UTXO that was created in 2015 and has never moved represents Bitcoin that has been held continuously for a decade. Tracking the age distribution of all UTXOs — "UTXO age bands" — reveals how much Bitcoin is held by long-term versus short-term holders at any given time.
The UTXO model has important privacy and security implications. Each UTXO is discrete and can be traced through the blockchain's history. Using multiple addresses and avoiding combining UTXOs from different sources helps preserve privacy. Bitcoin privacy tools like CoinJoin mix UTXOs from multiple users to break the transaction graph, making it harder to trace the history of any particular coin.
This definition is for informational and educational purposes only. Nothing on Finance Compass constitutes financial, investment, or trading advice. Always conduct your own research and consult a qualified professional before making financial decisions.