999 is a kind of real gold with a gold content of 99.9%. Gold is a simple form of chemical element gold, which is a soft, golden yellow and corrosion-resistant precious metal. Gold is a rarer, more precious and more valuable metal. Generally speaking, gold in the world is measured in ounces. In ancient China, gold was measured in ounces, which was a very important metal. It is not only a special currency for reserve and investment, but also an important material for jewelry industry, electronics industry, modern communication and aerospace industry. The chemical symbol of gold is Au, and the financial English code is XAU or gold. The name Au comes from a story of Aurora, the goddess of dawn in Roman mythology, which means shining dawn. There are two main types of gold trading in the gold market, namely spot trading and futures trading. Spot gold mainly refers to bullion, gold ingot, gold bar and gold coin. Most of the gold transactions newly mined by private or gold mining enterprises are physical transactions. The gold purchased by customers can be stored and transferred by themselves, or entrusted to a gold merchant for safekeeping. Spot transactions are generally delivered immediately after the transaction or completed within two days. Spot gold is traded at a special price, which is divided into two types in London gold market: pricing trading and quotation trading. The characteristic of pricing transaction is to provide customers with a single transaction price, that is, there is no bid-ask spread. According to the price of a single transaction, customers can buy and sell freely, and gold merchants only charge a small commission. Quoting transactions are divided into buying price and selling price. Pricing transactions are only valid for a specified period of time, ranging from one minute to one hour, depending on the supply and demand of market customers. The price of gold in other gold markets in the world is based on the pricing level of London market, and then look at the supply and demand situation in this market. Gold futures trading is not delivered immediately after trading, but both parties sign a contract, pay the deposit and then deliver on the scheduled date.