The Gann Square is a powerful tool in finance for determining support and resistance levels based on a stock's extreme price points. It works by extrapolating probable price levels from a central value, typically an all-time or cyclical high or low. This method tends to be more accurate when applied along the major axes of the square. To generate the Gann Square, the numbers are either incremented or decremented from the central value. This mathematical system is a valuable resource in predicting future price movements.