The strike price is the same as the exercise price and they are used interchangeably. For example, when you give an option to buy a stock, you have to specify the price at which you can buy the stock. This is different from the market price. The market price keeps changing but the strike price will not change. For example, an 1150 Call on Reliance Dec-18 option means that you have the right to buy Reliance at a strike price of Rs.1150 and this contract will expire on the last Thursday of December 2018. The value of the option will be determined by the stock price movement with reference to the strike price. For example, if you are holding a call option on Reliance Industries at a strike price of Rs.1150, then the option will become more valuable if the price of the stock moves up from Rs.1160 to Rs.1180. The option premium will go up accordingly.