You will sometimes hear someone say, in a loose conceptual sense, that credit cards have money in them. Of course we know that that isn't the case; our modern plastic card payment network relies on online transactions where the balance tracking and authorization decisions happen within a financial institution that actually has the money (whether it's your money or credit). There is an alternate approach though, one which has historically been associated with terms like "epurse" in the technology industry: what if the balance tracking and authorization decisions were actually made inside of the card?