Contract Size: The amount of the underlying asset covered by the option contract. This is 100 shares for one equity option unless adjusted for a special event, such as a stock split or a stock dividend, or otherwise special by the listing exchange.

Futures Contract: A standardized contract calling for the delivery of a specified quantity of a commodity at a specified date in the future.

Option Contract: A contract that represents the right, but not the obligation, to buy or sell a specified amount of an underlying security (stock, bond, futures contract, etc.) at a specified price within a specified time.