For example, a plastics producer could use commodity futures to lock in a price for buying natural gas by-products needed for production at a date in the future. The price of natural gas—like all petroleum products—can fluctuate considerably, and since the producer requires the natural gas by-product for production, they are at risk of cost increases in the future.
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.
For example: Tomatoes are cheap in July and will be expensive in January, you can’t buy them in July and take delivery in January, since they will spoil before you can take advantage of January’s high prices. The July price will reflect tomato supply and demand in July. The forward price for January will reflect the market’s expectations of supply and demand in January. July tomatoes are effectively a different commodity from January tomatoes.
The market value of that home may have doubled to $800,000. But because the down payment locked in a pre-determined price, the buyer pays $400,000. Now, in an alternate scenario, say the zoning approval doesn’t come through until year four. This is one year past the expiration of this option. Now the home buyer must pay the market price because the contract has expired. In either case, the developer keeps the original $20,000 collected.
Volatility also increases the price of an option. This is because uncertainty pushes the odds of an outcome higher. If the volatility of the underlying asset increases, larger price swings increase the possibilities of substantial moves both up and down. Greater price swings will increase the chances of an event occurring. Therefore, the greater the volatility, the greater the price of the option. Options trading and volatility are intrinsically linked to each other in this way.

The fee you are paying to buy the call option is called the premium (it's essentially the cost of buying the contract which will allow you to eventually buy the stock or security). In this sense, the premium of the call option is sort of like a down-payment like you would place on a house or car. When purchasing a call option, you agree with the seller on a strike price and are given the option to buy the security at a predetermined price (which doesn't change until the contract expires). 

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