If the stock’s closing price on expiration is $108, the $100 call option will end at a profit of $8 a share, or $800 per contract, while the $115 call option expires worthless and you keep the $500 made on the original sale. However, the options market allows you to assume either side of the trade. So becoming a successful options trader is no mean easy task

Source: The Real Articles: Finance | Stock Market Investing