Commodity meaning is generally described as any physical substance which may be food, grains or metals which are interchangeable to other commodities. Commodities are often used as the inputs for the production of other goods and services. Price of commodity depends on the demand and supply.
Commodities are usually saled and purchased through future contracts on exchanges, because exchanges standardize the measures about quality etc of a commodity that are supposed to traded through them. Commodity involves money value.