A statistical measure of the dispersion of returns for a given security or market index.
Volatility measures the degree of variation of a trading price series over time, usually measured by the standard deviation of logarithmic returns. High volatility indicates that the price of an asset can change dramatically over a short period in either direction, meaning the range between its bid and ask prices is wide. Conversely, low volatility means the asset's price tends to be more stable and predictable.