A contract giving the holder the right, but not the obligation, to purchase or sell a specific asset at a certain price (often at a certain future date). There are different kinds of options. For example, an employee stock option is an issuer security that gives an issuer’s employee (the holder) the right to buy the corporation's common shares at a certain price. In certain corporate transactions, an option can also refer to a put option or a call option for non-securities assets.

Options sold on a stock exchange are securities of an issuer giving the holder (an investor) the right to buy (also referred to as a call or call option) or sell (also referred to as a put or put option) a security of that issuer at a certain price for a limited period of time.