Smooths out the price across each period to reveal short, medium and long term trends and their relationship to each other. In principal, when the price is above a moving average the trend is up, when the price is below a moving average the trend is down.
When a short term MA crosses above a long term MA (a "golden cross") it is a strong buy signal. Conversely when a short term MA crosses below a long term MA (a "death cross") it is a strong sell signal.
Note that Moving Averages represent historical data and therefore are not strictly predictive in nature, but show trends that may be in action. Notably the 200 day MA will often be respected as support or resistance.
This tool is for educational purposes only and not a recommendation to buy or sell. Always do your own research before trading.