Bollinger Bands
Bollinger bands indicator was created by a financial analyst John Bollinger in 1980s. Bollinger bands are a complex technical analysis indicator which calculation is based on the volatility of the market (similar to Keltner channel indicator or Donchian channel indicator). The main idea behind the indicator is that it highlights the overbought and oversold conditions on the market but yet some other traders use it to identify strong trends (so as a matter of fact they use it as a trend-following indicator).