The right, but not the obligation, to buy (call option) or sell (put option) a specific amount of a given commodity, currency, debt, index, or stock at a specified price (the strike price) during a specified period of time.
Example, for stock options, the amount is usually 100 shares. Each option has a buyer, called the holder, and a seller, known as the writer. If the option contract is exercised, the writer is responsible for fulfilling the terms of the contract by delivering the shares to the appropriate party.
