Fibonacci retracement levels use horizontal lines based on Fibonacci percentages to indicate possible support and resistance areas. The most commonly used Fibonacci retracement percentages are 23.6%, 38.2%, 50%, 61.8%, and 78.6%. Fibonacci extensions apply the same percentages to project potential price targets or reversal areas as a trending move continues. Both tools provide areas of potential interest but should not be relied on exclusively to predict price behavior.