In the 19th century each dollar was pegged to a certain amount of silver or gold, same as many other currencies. You could go to a bank and redeem that amount of gold or silver for the bank note. That is what backing by something really is. Nowadays, you cannot do that, dollars, rubles, yuans are not pegged to anything, there is no backing. You can only purchase those goods, products and services at free market prices. You can do the same with cryptos, although it's still hard to find merchants who accept cryptos, but it's only because cryptos are a novel concept. The difference is, fiat currencies are legal tender in a certain jurisdiction, meaning all businesses have to accept them by law and you also pay taxes in them. But fiat currencies are not backed by those materials and goods you have listed above. 'fiat' means 'by decree' of the government.