A user deploying a full node may verify the entire transaction history of the bitcoin a sender wants them to accept. This enables the user to independently check that the bitcoin being offered is authentic, has not been double-spent and has never broken any other Bitcoin rule. This can be contrasted to receivers of, for example, gold or physical fiat money, whose verification might require specialist knowledge and expensive hardware such as gold assaying equipment. At any time, a user may also audit the total supply of the entire Bitcoin network. Again, this can be contrasted against receivers of gold or physical fiat money whose total supplies can only ever be estimated.