Futures is a contract that must be fulfilled in the future, not a specific commodity. The content of the contract is unified and standardized, but the price of the contract will fluctuate in different sizes due to changes in various market factors. The "goods" corresponding to this contract are called the subject matter. Generally speaking, the "goods" to be speculated in futures are the subject matter, which is embodied by contract symbols. Futures are divided into commodity futures and non-commodity futures. Commodity futures generally refer to precious metal futures (such as copper), agricultural and sideline products futures (such as soybeans) and energy futures (such as crude oil), while non-commodity futures refer to futures other than commodity futures, such as stock index futures, interest rate futures and foreign exchange futures.