Parabolic SAR was developed by Welles Wilder. It is a time/price trend following system that is always in the market. The actual Parabolic SAR dot on the chart is the stop and reverse point (SAR). In an uptrend, the SAR dot would be below the price. Once the stop is hit, a short position is taken (stop and reverse). Each day the stop moves in the direction of the trend (as indicated by Parabolic SAR).