What is an Option?

An option is a contract giving the buyer the right, but not the obligation, to buy or sell an underlying asset (a stock or index) at a specific price on or before a certain date (listed options are all for 100 shares of the particular underlying asset).
An option is a security, just like a stock or bond, and constitutes a binding contract with strictly defined terms and properties.
Options are the most versatile trading instrument ever invented. Since options cost less than stock, they provide a high leverage approach to trading that can significantly limit the overall risk of a trade or provide additional income. Simply put, op tion buyers have rights and option sellers have obligations. Option buyers have the right, but not the obligation, to buy (call) or sell (put) the underlying stock (or futures contract) at a specified price until the 3rd Friday of their expiration month. There are two kinds of options: calls and puts. Call options give you the right to buy the underlying asset. Put options give you the right to sell the underlying asset. It is essential to become familiar with the inner workings of both. Every strategy you learn from this point on depends on your thorough understanding of these two kinds of options.
There are no margin requirements if you want to purchase an option because your risk is limited to the price of the option. In contrast, option sellers receive a credit in their account for selling an option and get to keep this amount if the option expires worthless. However, option sellers also have an obligation to buy (put) or sell (call) the underlying instrument if their option is exercised by an assigned option holder. Therefore, selling an option requires a healthy margin.
To trade options, you must be acquainted with the select terminology of the option market. The price at which an underlying stock can be purchased or sold if the option is exercised is called the strike price. Options are available in several strike prices above and below the current price of the underlying asset. Stocks priced below $25 per share usually have strike prices at 2 ½ dollar intervals. Stocks priced over $25 usually have strike prices at $5 dollar intervals.
The date the option expires is referred to as the expiration date. A stock option expires by close of business on the 3rd Friday of the expiration month. All listed options have options available for the current month and the next month as well as specific future months. Each stock has a corresponding cycle of months that they offer options in. There are three fixed expiration cycles available. Each cycle has a four-month interval:

A. January, April, July and October
B. February, May, August and November
C. March, June, September and December

The price of an option is called the premium. An option's premium is determined by a number of factors including the current price of the underlying asset, the strike price of the option, the time remaining until expiration, and volatility. An option premium is priced on a per share basis. Each option on a stock corresponds to 100 shares. Therefore, if the premium of an option is priced at 2, the total premium for that option would be $200 (2 x 100 = $200). Buying an option creates a debit in the amount of the premium to the buyer's trading account. Selling an option creates a credit in the amount of the premium to the seller's trading account.

Example: Jane wants to buy a house. After a few weeks of searching, she discovers one she really likes. Unfortunately, she won't have enough money for a substantial down payment for another six months. So, she approaches the owner of the house and negotiates an option to buy the house within 6 months for $100,000. The owner agrees to sell her the option for $2,000.

Scenario 1: During this 6-month period, Jane discovers an oil field underneath the property. The value of the house shoots up to $1,000,000. However, the writer of the option (the owner) is obligated to sell the house to Jane for $100,000. Jan e buys the house for a total cost of $102,000-$100,000 for the house plus the $2,000 premium paid for the option. She promptly turns around and sells it for a million dollars for huge profit of $898,000 and lives happily ever after.

Scenario 2: Jane discovers a toxic waste dump on the property. Now the value of the house drops to zero and she obviously decides not to exercise the option to buy the house. In this case, Jane loses the $2,000 premium paid for the option to the owner of the property.