If you think the futures price will go up, go long (buy and open positions), go up (sell) and close positions, and earn: price difference = close positions-open positions.
If you think the futures price will fall, short (sell the position), fall (buy) and close the position, and earn: price difference = opening price-closing price.
It is generally easier to understand long futures (signing buy contracts), but it is not easy to understand short futures (signing sell contracts). Let's take shorting wheat as an example (the seller may not have the goods in his hand when signing the selling contract) to explain the principle of shorting futures:
When the price of wheat is 2000 yuan per ton, it is estimated that the price of wheat will fall. You signed a (first-class) contract with the buyer in the futures market, for example, you agreed to sell him 10 ton of standard wheat at a price of 2000 yuan per ton at any time within six months. (the value is 2000× 10 = 20000 yuan, calculated in 600 yuan. )
This is short selling (selling open positions). In practice, you are selling open wheat futures contracts.
Why should a buyer sign a contract with you? Because he's awesome.
When signing a contract, you don't necessarily have wheat in your hand (generally you don't really want to sell wheat). If you observe the market, as you wish, it drops to 1800 yuan per ton, you buy 100 tons of wheat per ton/800 yuan, and sell it to the buyer at 2000 yuan per ton, and the contract is fulfilled (yours
(2000-1800) × 10 = 2000 (yuan) (the handling fee is generally10 yuan, which is ignored).
This is profit liquidation. In fact, you are buying a futures contract to liquidate primary wheat.
The buyer (not specified) who signed the contract with you lost 2000 yuan (the handling fee was ignored).
In the whole operation, you only need to sell a hand of wheat in 2000 and buy a flat at 1800, which is very convenient.
After the futures are opened, they can be closed at any time before the delivery date, or they can be bought and sold multiple times on the same day (generally, there is no handling fee for closing positions on the same day). If the price of wheat rises within half a year, you have no chance to buy low-priced wheat to close your position, you will be forced to buy high-priced wheat to close your position (the contract must be closed at the expiration), you will lose money, and the buyer who signed with you will make a profit.
If you close your position at 2200, you will lose money:
(2200-2000)× 10=2000 (yuan)+10 yuan handling fee.
The buyer (not specified) who signed the contract with you earned 2000 yuan (the handling fee was ignored).