Futures is a standardized contract sale! Buying down refers to the right to sell the subject matter of the contract when you pay a certain percentage of deposit in the future, and buying up refers to the right to buy the subject matter of the contract when you pay a certain percentage of deposit in the future. To give a simple example, the current gold price is 243 yuan/gram, the trading volume is 1 1,000 grams, and the margin is 10%. If you think there is still room for gold to fall in the future, open a position and sell it now, and pay a deposit of 243 *100 *10% = 24,300 yuan.