Bitcoin operates using unspent transaction outputs (UTXOs) rather than traditional account balances, functioning more like digital cash than a bank ledger. This foundational architecture is widely considered one of Satoshi Nakamoto's most critical yet underrated innovations. The UTXO model was specifically designed to solve the double-spending problem without requiring a central authority. New research details the mechanics of this system and examines why numerous other blockchain networks have adopted similar output-based architectures for their own protocols.