A call option is an option contract that gives the owner (also called the buyer or holder) the right to buy (or ‘call’) a fixed amount of an underlying security at a stated price within a specified period of time. The owner of a call option has the right to call the security from the option writer (seller) at a fixed price called the exercise price or strike price. The writer of the call option is obligated to sell the security at a fixed price to the option holder if the holder of the call option chooses to exercise the call.