// Definition
Bollinger Bands are three lines drawn around price: a moving average in the middle and two bands above and below that widen and narrow with volatility.
Explained simply
The standard setting is a 20-period moving average with bands two standard deviations away. When volatility rises, the bands spread apart; when it falls, they squeeze together.
A tight squeeze often comes before a big move, although the bands alone do not tell you in which direction.
Tip
Touching the upper band is not a sell signal in a strong uptrend. Price can ride the band for a long time.
For education only, not financial advice. Trading is risky and you can lose money.