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.
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.
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. 
×