The most popular way of investing in gold is through the purchase of gold jewelry. Other ways include purchasing gold coins, bullion or bars, buying stocks in companies that extract gold, companies that sell gold jewelry, or by buying mutual funds that invest in precious metals, including gold. Investors may also buy exchange-traded gold funds, which may represent a certain holding or portfolio of gold purchases, as well as gold certificates that are issued by some banks, which represent a certain quantity of gold held by the bank.