Stock Options are a derivative of a stock, they are financial instruments that allow the option holder the right to buy or sell shares of a certain stock, at a specified price, for a specified period of time.
Stock options are traded on exchanges much like the stocks (Apple, Google, Amazon, etc.) themselves. The price of the option itself can be higher or lower than the original price when it was first listed. Most listed options conform to an options calendar and typically expire a specific date. Prior to this expiration date, the option holder has to decide whether to exercise the option by buying or selling the number of shares associated with the option, selling the option, or simply letting it expire.