For example, if you bought a long call option (remember, a call option is a contract that gives you the right to buy shares later on) for 100 shares of Microsoft stock at $110 per share for December 1, you would have the right to buy 100 shares of that stock at $110 per share regardless of if the stock price changed or not by December 1. For this long call option, you would be expecting the price of Microsoft to increase, thereby letting you reap the profits when you are able to buy it at a cheaper cost than its market value. However, if you decide not to exercise that right to buy the shares, you would only be losing the premium you paid for the option since you aren't obligated to buy any shares. 
Because options prices can be modeled mathematically with a model such as the Black-Scholes, many of the risks associated with options can also be modeled and understood. This particular feature of options actually makes them arguably less risky than other asset classes, or at least allows the risks associated with options to be understood and evaluated. Individual risks have been assigned Greek letter names, and are sometimes referred to simply as "the Greeks."
Still other traders can make the mistake of thinking that cheaper is better. For options, this isn't necessarily true. The cheaper an option's premium is, the more "out of the money" the option typically is, which can be a riskier investment with less profit potential if it goes wrong. Buying "out of the money" call or put options means you want the underlying security to drastically change in value, which isn't always predictable. 

* Sell orders are subject to an activity assessment fee (from $0.01 to $0.03 per $1,000 of principal). Trades are limited to online domestic equities and options and must be used within two years. Options trades are limited to 20 contracts per trade. Offer valid for new and existing Fidelity customers opening or adding net new assets to an eligible Fidelity IRA or brokerage account. Deposits of $50,000-$99,999 will receive 300 free trades, and deposits of $100,000 or more will receive 500 free trades. Account balance of $50,000 of net new assets must be maintained for at least nine months; otherwise, normal commission schedule rates may be retroactively applied to any free trade executions. See Fidelity.com/ATP500free for further details and full offer terms. Fidelity reserves the right to modify these terms and conditions or terminate this offer at any time. Other terms and conditions, or eligibility criteria may apply.
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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