The basic interpretation of Bollinger Bands is that, the prices tend to stay within the upper and lower bands. The Bollinger Bands have unique characteristic that the spacing between the bands varies based on the volatility of the currency prices. During high volatility periods, the bands widen to become more forgiving. Similarly during periods of low volatility, the bands narrow to contain currency prices. The bands are draw with two standard deviations above and below a SMA. They indicate a "sell" when above the moving average (or close to the upper band) and a "buy" when below it (or close to the lower band). The bands are used by some forex traders in conjunction with other analyses, including RSI, MACD, CCI, and Rate of Change.