What is BB?
Bollinger Bands (BB)
Bollinger Bands measure the volatility of the market, as well as overbought and oversold conditions. They are made up of three lines - an SMA (the middle band), and an upper and lower band. The settings may vary, but typically the upper and lower bands are two standard deviations away from the middle band. As volatility increases and decreases, the distance between the bands increases and decreases as well.
Generally, the closer the price is to the upper band, the closer to overbought conditions the charted asset may be. Conversely, the closer the price is to the lower band, the closer to oversold conditions it may be. For the most part, the price will stay within the bands, but on rare occasions, it may break above or below them. While this event may not be a trading signal in itself, it can act as an indication of extreme market conditions.