About commodities

— -- Commodities are goods such as crude oil, wheat, metals, orange juice, live cattle and pork bellies. They are bought and sold by producers, by companies that use the goods, and by investors, or traders.

Commodities are traded in two types of markets: the spot or cash market, where goods are bought and sold for immediate delivery, and the futures market, where contracts are for future delivery. Those futures contracts obligate a seller to deliver a specified amount of a commodity to a buyer on a specified date in the future.

Businesses use futures contracts to lock in prices, so their future costs of goods are more predictable.

Producers of the commodities use futures contracts to lock in a profit, agreeing to deliver their goods for a guaranteed price in the future.

Traders buy and sell futures contracts to try to make money on price changes. The last thing they want is to own 44,000 pounds of aluminum in a warehouse somewhere. But those traders do help make the commodities markets more efficient, by providing more potential buyers and sellers for every contract.

USATODAY.com's commodities page lists futures contract prices for 21 key commodities, from aluminum to wheat. Prices listed are for the "near term" contract, that is, the contract that expires next, usually in the current month or the next month. You can click on the name of the commodity to find out the quantity of each contract and how the price is quoted.