In the millennia that humans have roamed the earth, the world has cycled through a number of obscure, even unusual, currencies. The ancient Mayans are believed to have used chocolate as money; traders in the Solomon Islands favored dolphin teeth. Yap islanders, at least those with strong backs, tended toward massive stones. The British pound, the oldest global currency still used today, anchored the global economy, until its fall in the early, mid, and late 20th century.
Today, it is the dollar that reigns supreme. The world’s biggest economy (probably) can print greenbacks at will. The dollar is the world’s most widely held reserve currency and also dominates global trade. Oil, no matter how many times Saudi Arabia and China hold their breath, is still priced in the dollar. Most other major commodities are, too. As is pretty much everything else.