Crude oil futures are generally estimated prices, which refer to the purchase and sale of crude oil for a period of time. Spot prices refer to the market price when the futures expire. If the market price is higher than the futures price, it is a posthumous price. If it is lower than the futures price, it is a shortfall.

Eighty US dollars per barrel, the market price is US$40, a shortfall of US$40 per barrel, conversely, the futures price is US$40, the spot price is US$80, and the premium is US$40 per barrel.