Bitcoin consists of three levels: UTXO, POW, and longest chain. -The UTXO module achieves decentralization, that is, the distributed private individualization of the account system. -The longest chain achieves distributed trust verification, completes decentralized notarization, and the unpredictable longest chain achieves decentralized confirmation of rights. -POW is essentially a distributed job that earns money through working, with rewards from Coinbase and TX fees. Namely, the unpredictable, uncertain, and decentralized 'longest chain' of Bitcoin is the invisible boss of Bitcoin. And the miners working at POW are truly advanced workers. And UTXO is the served protagonist on the system, with all private account permissions in UTXO's own hands. Bitcoin is an adaptive decentralized cryptocurrency system. And by understanding these logics, we can better design excellent decentralized adaptive cryptocurrency systems.