Money not subject to massive inflation and deflation as its value is not tied to the amount of gold coming out of the ground, but rather to the economy.
Gold-backed current sucks. When new gold is discovered it's value swings wildly. When no gold is being discovered but the economy is going great there is a shortage of it so deflation sets in, causing loans to balloon in real terms.
Something that only has value because you can buy things with it. Contrast with gold-backed dollar or silver-backed dollar, which have value because they may be redeemed for a fixed quantity of a commodity good.
