Newbie question. AFAIK, each US banknote has a unique serial number. Is the same true for bitcoin? Does each bitcoin have a unique identifier, regardless who owns it? Does each satoshi have a unique identifier?
Fiat is centralized and that is why it has serial number. Bitcoin is not like that because it is decentralized and doesn't have a unique identifier. Bitcoin is always locked in the blockchain and it is only the one who has the private keys to that address which the bitcoin is in that can use it to unlock the bitcoin for spending. Fiat currency is different from digital currency.