Implied volatility seems key to trading options.
As I understand it IV, is as it sounds, the implied volatility of an option and it either increases or decreases the price of said option. IV is equated into the option premium.
So my question is: What determines IV for any given option. Where does the IV comes from? Does it have to do with the volume of an option, or demand for an option at any one time?. Or perhaps there is a formulae for calculation the IV of any option?