What's a Commodity?

A physical substance, such as food, grains, and metals, which is interchangeable with another product of the same type. The price of the commodity is subject to supply and demand. That is, if the supply of the commodity rises, the price will decline. If, for example, more countries start to produce coffee, the price paid to farmers will go down (as has happened recently with the emergence of large coffee harvests from Vietnam). Because commodities are pretty much the same regardless of where they're from (if you are buying wheat, it doesn't matter if that wheat comes from Argentina or North Dakota), their price can change dramatically with changes in supply.

Some of the commodities that circulated in the "Atlantic system" were in fact stimulants: sugar, coffee, and tobacco.