A call option is an investment strategy, where the buyer of the option is betting that the underlying value of the asset (stock, bond, commodity) is going to rise. In this investment, the call option guarantees the buyer THE OPTION to buy the asset at as specified price within a specified time period.

Ex: If the stock price today is $50.00, and you purchase a call option on that stock in hopes that the price will rise, you will be able to buy that stock at $50.00 for a certain time period (call period) after the purchase date. If the price rises to $60.00, you are able to buy it at $50.00, making $10.00 per share.

Keep in mind call options are not free, there is a 'Premium' involved at the purchase date.