Bollinger Bands are a technical analysis tool developed by John Bollinger in the 1980s for trading stocks. The bands comprise a volatility indicator that measures the relative high or low of a security’s price in relation to previous trades. voladity is measured using standard deviation, which changes with increases or decreases in volatility. The bands widen when there is a price increase, and narrow when there is a price decrease. Due to their dynamic nature, Bollinger Bands can be applied to the trading of various securities. Bollinger Bands are comprised of three lines – the upper, middle, and lower band. The middle band is a moving average, and its parameters are chosen by the trader. The upper and lower bands are positioned on either side of the moving average band. The trader decides the number of standard deviations they need the volatility indicator set at. The number of standard deviations, in turn, determines the distance between the middle band and the upper and lower bands. The position of these bands provides information on how strong the trend is and the potential high and low price levels that may be expected in the immediate future.