A commodity is a basic good that can be bought and sold, especially something like wheat, oil, copper, or cotton that comes from farms or mines. What makes something a commodity is that one batch is pretty much the same as another: a barrel of oil from Texas works just as well as a barrel from Saudi Arabia, and a bushel of corn from Iowa is interchangeable with one from Nebraska.

Farmers and mining companies produce commodities, then sell them to manufacturers who turn them into finished products. The wheat commodity becomes bread, the copper commodity becomes wiring, the cotton commodity becomes T-shirts. Because commodities are so interchangeable, their prices rise and fall based on how much people want them and how much is available. When a drought reduces the corn harvest, corn prices spike. When new oil wells open, oil prices might drop.

The word can also describe anything treated as interchangeable. If a company treats its workers like commodities, it means the company doesn't value their individual talents or personalities, acting as if any worker could easily replace another. This use of the word usually carries a negative feeling, since most people don't want to be treated as identical and replaceable.

Throughout history, control over valuable commodities like salt, spices, gold, and oil has shaped world events, sparked wars, and built empires.