Products that can be traded on a commodities exchange, for example, agricultural products, metals, petroleum, gasoline, heating oil, and natural gas. The term commodity may refer to physical products, such as oil, gasoline, or building supplies that are purchased in the cash market that have nothing to do with a futures exchange. The term can also refer to the fact that over time, as more companies enter a market, competition drives prices down, resulting in a product moving from being profitable to being little more than a commodity.