Purchasing a call option is essentially betting that the price of the share of security (like a stock or index) will go up over the course of a predetermined amount of time. For instance, if you buy a call option for Alphabet (GOOG) at, say, $1,500 and are feeling bullish about the stock, you are predicting that the share price for Alphabet will increase. 
$4.95 commission applies to online U.S. equity trades in a Fidelity retail account only for Fidelity Brokerage Services LLC retail clients. Sell orders are subject to an activity assessment fee (from $0.01 to $0.03 per $1,000 of principal). Other conditions may apply. See Fidelity.com/commissions for details. Employee equity compensation transactions and accounts managed by advisors or intermediaries through Fidelity Clearing & Custody Solutions® are subject to different commission schedules.

With options markets, as with futures markets, long and short refer to the buying and selling of one or more contracts, but unlike futures markets, they do not refer to the direction of the trade. For example, if a futures trade is entered by buying a contract, the trade is a long trade, and the trader wants the price to go up, but with options, a trade can be entered by buying a Put contract, and is still a long trade, even though the trader wants the price to go down. The following chart may help explain this further:
Options are contracts giving the owner the right to buy or sell an asset at a fixed price (called the “strike price”) for a specific period of time. That period of time could be as short as a day or as long as a couple of years, depending on the option. The seller of the option contract has the obligation to take the opposite side of the trade if and when the owner exercises the right to buy or sell the asset. For more information, check out the Ally Invest Options Playbook here: https://www.optionsplaybook.com/
The information contained in this article is provided for general informational purposes, and should not be construed as investment advice, tax advice, a solicitation or offer, or a recommendation to buy or sell any security. Ally Invest does not provide tax advice and does not represent in any manner that the outcomes described herein will result in any particular tax consequence. Prospective investors should confer with their personal tax advisors regarding the tax consequences based on their particular circumstances.

As shown above, a long options trade has unlimited profit potential, and limited risk, but a short options trade has limited profit potential and unlimited risk. However, this is not a complete risk analysis, and in reality, short options trades have no more risk than individual stock trades (and actually have less risk than buy and hold stock trades).
Research is provided for informational purposes only, does not constitute advice or guidance, nor is it an endorsement or recommendation for any particular security or trading strategy. Research is provided by independent companies not affiliated with Fidelity. Please determine which security, product, or service is right for you based on your investment objectives, risk tolerance, and financial situation. Be sure to review your decisions periodically to make sure they are still consistent with your goals.
You also can limit your exposure to risk on stock positions you already have. Let’s say you own stock in a company but are worried about short-term volatility wiping out your investment gains. To hedge against losses, you can buy a “put” option that gives you the right to sell a particular number of shares at a predetermined price. If the share price does indeed tank, the option limits your losses, and the gains from selling help offset some of the financial hurt.
When a trader buys an options contract (either a Call or a Put), they have the rights given by the contract, and for these rights, they pay an upfront fee to the trader selling the options contract. This fee is called the options premium, which varies from one options market to another, and also within the same options market depending upon when the premium is calculated. The option's premium is calculated using three main criteria, which are as follows:
For example, if you believe the share price of a company currently trading for $100 is going to rise to $120 by some future date, you’d buy a call option with a strike price less than $120 (ideally a strike price no higher than $120 minus the cost of the option, so that the option remains profitable at $120). If the stock does indeed rise above the strike price, your option is in the money.
Equity options today are hailed as one of the most successful financial products to be introduced in modern times. Options have proven to be superior and prudent investment tools offering you, the investor, flexibility, diversification and control in protecting your portfolio or in generating additional investment income. We hope you'll find this to be a helpful guide for learning how to trade options.
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.