Bollinger bands
Bollinger bands are yet another technical indicator. Yes, there are thousands of them. This one is named after its inventor and indicates a range for the price of a financial security. It consists of three parts, as follows:
A simple moving average
An upper band of two standard deviations above this moving average—the standard deviation is derived from the same data with which the moving average is calculated
A lower band of two standard deviations below the moving average