The Bollinger Band is one of the most-used and most-misread indicators in retail trading. Used as a crystal ball, it will hurt you. Used as a ruler for volatility, it's genuinely useful.
What it is
A Bollinger Band is just a moving average with a volatility envelope: the 20-period average of price, plus and minus two standard deviations. The bands widen when price is choppy and contract when it's calm. That's all it is — a statistical measure of where price sits relative to its own recent behaviour.
The myth
The popular reading — "price tagged the upper band, so it's overbought, so sell / short it" — is where most people lose money. A band tag is not a reversal signal. In a genuine trend or a short squeeze, price will walk the band: ride along or above the upper line for many sessions while the trend continues. Treating the upper band as a ceiling in a strong move is a fast way to get run over.
The useful reading
Where the band earns its keep is as context for pricing, not direction. An upper-band tag tells you price is statistically stretched relative to its recent range. Pair that with elevated implied volatility, and you have a moment when optionality is both extended and expensive — a sensible place to sell premium against an existing position, rather than to bet on a reversal outright.
The discipline
Because band-walks are real, anything you sell at the upper band needs a plan for the case where price keeps going: roll early, size small, and define your exit before you enter. The band improves your odds and your pricing; it does not remove your risk.
I use exactly this — an upper-band tag under high IV as a sell trigger — as the financing leg of a larger structure. The full method is here: The Reaper's Inverted Diagonal.