Decide whether you think a commodity will sell for more or for less at some designated time in the future, then buy either a “put” or a “call” option. For example, you think that corn will cost more three months from now than it does now, so you will buy a “call” option on 100 bushels of corn which, in effect, locks in the cost of that commodity. Before the option expires, hopefully the price will go up, so your option will be worth more. Conversely, you will buy a “put” option if you think the price of the commodity will be less than it is today.

The price at which you agree to buy the underlying security via the option is called the "strike price," and the fee you pay for buying that option contract is called the "premium." When determining the strike price, you are betting that the asset (typically a stock) will go up or down in price. The price you are paying for that bet is the premium, which is a percentage of the value of that asset. 

For instance, it is possible to construct an option strategy in the futures markets that is affordable without sacrificing the odds of success...but with the convenience comes theoretically unlimited risk. This is easier than it sounds, similar to the way you would borrow money to pay for a house or a car, you can borrow money from the exchange to pay for long commodity option trades. There are an unlimited number of combinations of self-financed trades but they are typically going to involve more short options than long options, or at least as much premium collected on the sold options than that paid for the longs. In essence, the money brought in through the sale of the short options goes to pay for the futures options that are purchased. The result is a relatively close-to-the-money option with little out of pocket expense but theoretically unlimited risk beyond the strike price of the naked short options.
In case of futures, a buyer of a contract is said to be “long position holder” and a seller is “Short position holder”. In the case of futures, to avoid the risk of defaulting contract involves both parties lodging a certain percentage margin of value of contract with a mutually trusted third party. Generally, in gold futures trading, margin varies between 2%-20% depending on the volatility of gold in spot market.
The currency market, or foreign exchange market ("forex"), was created to facilitate the exchange of currency that becomes necessary as the result of foreign trade. That is, when an entity in one country sells something to an entity in another country, the seller earns that foreign currency. When China sells t-shirts to Walmart, for example, China earns US dollars. When Toyota wants to build a factory in the US, it needs dollars. It may get those from its local bank, which in turn will obtain them in the international currency market. This market exists to facilitate these types of exchanges.

The potential home buyer would benefit from the option of buying or not. Imagine they can buy a call option from the developer to buy the home at say $400,000 at any point in the next three years. Well, they can—you know it as a non-refundable deposit. Naturally, the developer wouldn’t grant such an option for free. The potential home buyer needs to contribute a down-payment to lock in that right.

Trading in commodity futures contracts can be very risky for the inexperienced. The high degree of leverage used with commodity futures can amplify gains, but losses can be amplified as well. If a futures contract position is losing money, the broker can initiate a margin call, which is a demand for additional funds to shore up the account. Further, the broker will usually have to approve an account to trade on margins before they can enter into contracts.
When buying or selling options, the investor or trader has the right to exercise that option at any point up until the expiration date - so simply buying or selling an option doesn't mean you actually have to exercise it at the buy/sell point. Because of this system, options are considered derivative securities - which means their price is derived from something else (in this case, from the value of assets like the market, securities or other underlying instruments). For this reason, options are often considered less risky than stocks (if used correctly).