Tells Me: The price is generally in an established trend (bullish or bearish) for the time horizon represented by the moving average period (21, 50 or 200 bars). Moving averages are used to smooth out the volatility or "noise" in the price series, to make it easier to discover the underlying trend. By plotting the average price over the last several bars, the line is less "jerky" than plotting the actual prices. A bullish event is generated when the price crosses above the moving average, and in this state, the price is likely in an established uptrend. The opposite is true when the price crosses below the moving average, triggered a bearish event.