A commodity is a tradeable product – something that can be bought or sold. Products that can be defined as commodities include oil, grain, coffee and, of course, precious metals. For example, silver is one of the world's most widely traded commodities and is considered one of the safest options for investors. Often a commodity is interchangeable with other commodities of the same type. Using silver coins as an example, a coin may be traded for cash or for another type of silver coin.