Another example involves buying a long call option for a $2 premium (so for the 100 shares per contract, that would equal $200 for the whole contract). You buy an option for 100 shares of Oracle (ORCL) for a strike price of $40 per share which expires in two months, expecting stock to go to $50 by that time. You've spent $200 on the contract (the $2 premium times 100 shares for the contract). When the stock price hits $50 as you bet it would, your call option to buy at $40 per share will be $10 "in the money" (the contract is now worth $1,000, since you have 100 shares of the stock) - since the difference between 40 and 50 is 10. At this point, you can exercise your call option and buy the stock at $40 per share instead of the $50 it is now worth - making your $200 original contract now worth $1,000 - which is an $800 profit and a 400% return.
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).