The dollar is, technically, a currency. A currency is a government substitute for money. But gold is money.
Now, why do I say that?
Historically, many things have been used as money. Cattle have been used as money in many societies, including Roman society. That's where we get the word "pecuniary" from: the Latin word for a single head of cattle is pecus. Salt has been used as money, also in ancient Rome, and that's where the word "salary" comes from; the Latin for salt is sal (or salis). The North American Indians used seashells. Cigarettes were used during WWII. So, money is simply a medium of exchange and a store of value.
By that definition, almost anything could be used as money, but obviously, some things work better than others; it's hard to exchange things people don't want, and some things don't store value well. Over thousands of years, the precious metals have emerged as the best form of money. Gold and silver both, though primarily gold.