Pay a “premium” wherever you buy a commodity option. Let's say you purchase a “call” option on 100 bushels of corn, and the premium is $2 per bushel. You will pay $200 for the right to exercise your option until it expires. That is your only cost to purchase the option, except for whatever commission you had to pay to your brokerage company. Even if you choose not to exercise the option before it expires, your investment will be limited to the $200 premium plus commission.

All investors should know how to trade options and have a portion of their portfolio set aside for option trades. Not only do options provide great opportunities for leveraged plays; they can also help you earn larger profits with a smaller amount of cash outlay. What’s more, option strategies can help you hedge your portfolio and limit potential downside risk.

So, call options are also much like insurance - you are paying for a contract that expires at a set time but allows you to purchase a security (like a stock) at a predetermined price (which won't go up even if the price of the stock on the market does). However, you will have to renew your option (typically on a weekly, monthly or quarterly basis). For this reason, options are always experiencing what's called time decay - meaning their value decays over time. 
As shown above, a long options trade has unlimited profit potential, and limited risk, but a short options trade has limited profit potential and unlimited risk. However, this is not a complete risk analysis, and in reality, short options trades have no more risk than individual stock trades (and actually have less risk than buy and hold stock trades).
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 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.