For example, if you believe the share price of a company currently trading for $100 is going to rise to $120 by some future date, you’d buy a call option with a strike price less than $120 (ideally a strike price no higher than $120 minus the cost of the option, so that the option remains profitable at $120). If the stock does indeed rise above the strike price, your option is in the money.
Sometimes corporations enter the forex market in order to hedge their profits. A US company with extensive operations in Mexico, for example, may enter into a futures contracts on US dollars. So, when it comes time to bring those Mexican profits home, the profits earned in pesos will not be subject to unexpected currency fluctuations. The futures contract is a way of securing an exchange rate and eliminating the risk that peso will lose value versus the dollar, making those profits worth less in dollars.
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. 
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