Stock options are generally granted by your employer as part of an incentive-based pay package. The idea is that an individual is granted the option to buy a certain number of shares at a certain price, say $10 per share. Usually there is a vesting period before the options can be exercised. So, imagine you are granted 100 options at a sale price of $10 per share, with a vesting period of 1 year. If after one year, the stock is trading for $15 per share, then you can sell your options at that price and make $500 profit.