The bullion market is just one of several ways to invest in gold and silver. Other options include exchange-traded funds, futures, options and mutual funds. These can be more appealing to investors, because they offer greater flexibility. Gold and silver are also bought and sold as coins (platinum and palladium coins exist but are rarer): and gold is traded in the form of small grains. The simple aim of buying bullion is to buy when prices are low and sell when prices are high. However life and the markets are never simple or easy to predict.