Fibonacci Numbers are commonly used in Technical Analysis with or without a knowledge of Elliot Wave Analysis to determine potential support, resistance, and price objectives.
The most popular Fibonacci Retracements are 61.8% and 38.2%
61.8% retracements imply a new trend is establishing itself.
38.2% retracements usually imply that the prior trend will continue
38.2% retracements are considered natural retracements in a healthy trend.
Fibonacci Retracements can be applied after a decline to forecast the length of a counter-trend bounce.
The 50% retracement is not based on a Fibonacci number. Instead, this number stems from Dow Theory's assertion that the Averages often retrace half their prior move.