Bitcoin's UTXO (Unspent Transaction Output) accounting model, designed by Satoshi Nakamoto, continues to underpin major cryptocurrencies including Litecoin, Dogecoin and Zcash. Unlike traditional account-based systems that track total balances, the UTXO model treats funds as discrete spendable outputs, each representing a specific amount locked to a particular address. The architecture was central to solving the double-spending problem in decentralized networks without requiring a trusted intermediary. By tracking individual outputs rather than aggregate account totals, the UTXO model enables nodes to independently verify that no coins are spent more than once across the entire blockchain.