Implied Volatility (IV) is an estimation of how much the market expects the price of the underlying asset to fluctuate in the future. A high number suggests a large deviation from the current price is likely, and vice-versa.

IV is expressed as a percentage and represents the expected annual price change within a year. For example, if an asset is trading at $100 and has an IV of 35% it means that the price is expected to stay within the range of $65 and $135, within one year, with one standard deviation probability (i.e. 68.27%).