Parabolic Indicator

A technical analysis strategy that uses a trailing stop and reverse method called "SAR," or stop-and-reversal, to determine good exit and entry points.

Investopedia Says:
This method was developed by J. Wells Wilder. Basically, if the stock is trading below the parabolic SAR you should sell. If the stock price is above the SAR then you should buy (or stay long).

Related Links:
Take a closer look at this indicator, which during a trending period, is a very useful and accurate tool. Introduction to the Parabolic SAR
The important decision to exit a position must be based on more than emotion if you want to be a disciplined trader. Trailing-Stop Techniques
Read the case against this well-established indicator. Candle Sheds More Light Than The MACD