It is the same for the farmer or producer. They have an interest to fix prices for future products now, too. Let us assume we have a farm and we plan what to seed for the next year. If we do not know at what price we can sell our products it brings danger to us. It would be possible that we seed corn and that the corn prices are down at the time we want to harvest the corn and sell it. Maybe we better seed soybean or other crops? With a future contract we can sell the crops at the moment we seed it and we can be sure for what price we sell it later on. For example we sell a corn futures contract with a delivery date of August 2018 with 5.000 bushels now for 353 bp. This gives us security for our planing now because we can be sure how much money we get in August 2018. The same is true for Gold producers, they can plan their mining activity or Oil producers and all other kind of producers.
Speculators play another important role in the Futures market. The producer and the industrial company only want to buy or sell Futures contracts to a specific point of time, for example when they harvest their field or when they plan to produce or stock their depots. If all farmers harvest corn in mid-September and sell their corn the price goes down as the supply overexeeds demand. This is where the speculator comes in and acts as buyer for the seller (the farmer) and as seller for the buyer (the industrial producer). The speculator helps to ensure an ongoing supply of commodities, without the speculator it would not be possible for the farmer or industrial producer to run their business.
A futures contract is a standardized forward contract which can be easily traded between parties other than the two initial parties to the contract. The parties initially agree to buy and sell an asset for a price agreed upon today (the forward price) with delivery and payment occurring at a future point, the delivery date. Because it is a function of an underlying asset, a futures contract is a derivative product (LINK https://en.wikipedia.org/wiki/Futures_contract ).
Exchange traded Futures are highly regulated and liquid. They contain -due to a system of insurance and reassurance- a smaller counterpart risk than many other investment categories. Even through the great repression from mid-1929 to mid-1931 there was no issue with the delivery of Futures contracts.