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.
Listed options have been available since 1973, when the Chicago Board Options Exchange, still the busiest options exchange in the world, first opened.