Drawing Tools can be applied, moved, and formatted, directly on a chart, providing tremendous flexibility. Many drawing tools allow you to analyze new data on a chart by extending the drawing object to the left or to the right of the chart. You can use them to call attention to any area of a chart you wish.
This tool allows for calculating support/resistance levels for an existing trend and possible breakout locations based on Fibonacci numbers.
Fibonacci Retracements are displayed by first drawing a trendline between two extreme points, for example, a trough and opposing peak. A series of nine horizontal lines are drawn intersecting the trendline at the Fibonacci levels of 0.0%, 23.6%, 38.2%, 50%, 61.8%, 100%, 161.8%, 261.8%, and 423.6%. (Some of the lines will probably not be visable because they will be off the scale.)
After a significant price move (either up or down), prices will often retrace a significant portion (if not all) of the original move. As prices retrace, support and resistance levels often occur at or near the Fibonacci Retracement levels