An equity option allows investors to fix the price for a specific period of time at which an investor can purchase or sell 100 shares of an equity for a premium (price), which is only a percentage of what one would pay to own the equity outright. This allows option investors to leverage their investment power while increasing their potential reward from an equity’s price movements.

An option remains valuable only if the stock price closes the option’s expiration period “in the money.” That means either above or below the strike price. (For call options, it’s above the strike; for put options, it’s below the strike.) You’ll want to buy an option with a strike price that reflects where you predict the stock will be during the option’s lifetime.
The price at which you agree to buy the underlying security via the option is called the "strike price," and the fee you pay for buying that option contract is called the "premium." When determining the strike price, you are betting that the asset (typically a stock) will go up or down in price. The price you are paying for that bet is the premium, which is a percentage of the value of that asset. 
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