This is a premium, and there is a price difference between spot and futures. In the futures market, if the spot price is lower than the futures price, the basis is negative, and the price of the forward futures contract is higher than that of the recent futures contract. This situation is called "futures premium", also known as "spot discount", and the part where the forward futures price exceeds the recent futures price is called "premium". If the forward futures contract price is lower than the recent futures contract price and the spot price is higher than the forward futures price, the basis is positive, which is called "futures discount" or "spot premium". The part where the forward futures contract price is lower than the recent futures price is called the "futures discount rate". Futures discount can not only refer to the price relationship between spot and delivery month, but also refer to the price relationship between alternative delivery and standard delivery in physical delivery, and also refer to the price relationship between different delivery places of goods. Premium reflects the specific price relationship between a commodity and a target under certain conditions, so the change of premium has a great influence on futures prices, and investors are also very sensitive to the change of premium. Premium can be divided into four categories: first, premium between spot price and futures price; Second, the premium between alternative delivery and standard delivery; Third, the premium of cross-year delivery; Fourth, the premium between different delivery places.