In financial terms, this is called leverage . Every futures contract is traded on an exchange according to a fixed set of rules. Each contract has very tight specifications, among them the standard size of the contract. For example, one U.S. wheat contract always represents 5,000 bushels of wheat. Almost all futures and options contracts are in U.S. dollars.
Most contracts expire within a year or so, though some do have a longer shelf life.
After that, contracts aren't yet available, but March 2003 wheat futures will become available and will be listed on the exchange as time rolls on and as the nearby contracts expire. Most of the trading activity tends to focus on the nearer term contracts, while those further away in time are obviously a more difficult bet and don't attract as much trading activity or liquidity . Anticipating what raw commodities will cost fuels the futures market. Commodities prices are basically determined by simple supply and demand . For many commodities, particularly agricultural ones, the annual supply and demand cycle is seasonal.