Realized Volatility

Realized Volatility is the actual movement that occurs in a given underlying over a defined past period.

Sometimes referred to as the historical volatility, this term usually used in the context of derivatives. While the implied volatility refers to the market's assessment of future volatility, the realized volatility measures what actually happened in the past.

One method to calculate it: Annualised standard deviation of daily (log) returns calculated from a data set over a specified fixed period of time.