the value is attached to another financial contract of securities, such as the futures contract of pork belly, which says that you must buy 1 kg of pork belly at 1 rmb in three months. The value of this contract mainly changes according to the value of pork belly. For example, now 1 kg of pork belly is 12 pieces, so you can have this contract after three months. Then this contract is about 2 yuan (the actual value needs discount interest rate, inventory cost, bonus and so on are not explained here), and the price change of pork belly directly affects the price change of this contract, so' pork belly' is the basic asset, while' pork belly forward' is the derivative tool of pork belly. (Actually, there is a pork belly forward in the financial market, but I don't know the price, because I don't buy food very much ...)