For example, my apple is not ripe yet, and it may not mature until the end of the year. However, you want to buy apples now, and promise to wait until the apples are ripe for five yuan/catty. Of course, I also agree with this price. Reach a trading intention.

At the end of the year, the apple matured and we delivered it in kind. We'll settle the money and it's over.

Of course, in the real world, you can resell the purchase right of Apple to others in the market to get the difference.

At the end of the year, the price of apples is only 1 yuan/kg, and you can choose not to make delivery if you default at maturity.

Of course, I can also choose the default. If the market price of Apple becomes 25 yuan/Jin at the end of the year, I can also breach the contract. Of course, this will be forced to close the position, and the deposit may be gone.