Key Standards & Protocols
UTXO (Unspent Transaction Output)
Bitcoin's accounting model where wealth is the sum of unspent outputs your keys can sign — enabling privacy and granular coin control.
Definition
The accounting model used by Bitcoin and derived protocols, where each transaction consumes previous unspent outputs and creates new ones. Unlike Ethereum's account-based model, UTXO-based systems have no persistent "balance" — your wealth is the sum of all unspent outputs your keys can sign. The UTXO model has profound privacy and security implications: it naturally supports CoinJoin mixing, enables granular coin control, and makes the relationship between transactions explicit. Understanding UTXO management is essential for sophisticated custody operations.