The Pencil tool works primarily the same way in Adobe Illustrator and InDesign. It lets you draw open and closed paths as if you were drawing with a pencil on paper. It is most useful for fast sketching or creating a hand-drawn look. Once you draw a path, you can immediately change it if needed.
Anchor points are set down as you draw with the Pencil tool; you do not determine where they are positioned. However, you can adjust them once the path is complete. The number of anchor points set down is determined by the length and complexity of the path and by tolerance settings in the Pencil Tool Preferences dialog box. These settings control how sensitive the Pencil tool is to the movement of your mouse or graphics-tablet stylus.
Depending on where you begin to redraw the path and in which direction you drag, you may get unexpected results. For example, you may unintentionally change a closed path to an open path, change an open path to a closed path, or lose a portion of a shape.
Controls how far you have to move your mouse or stylus before a new anchor point is added to the path. The higher the value, the smoother and less complex the path. The lower the value, the more the curves will match the pointer’s movement, resulting in sharper angles. Fidelity can range from 0.5 to 20 pixels.
Controls the amount of smoothing applied when you use the tool. Smoothness can range from 0% to 100%. The higher the value, the smoother the path. The lower the value, the more anchor points are created, and the more the line’s irregularities are preserved.
Fill New Pencil Strokes
(Illustrator only) Applies a fill to pencil strokes you draw after selecting this option, but not to existing pencil strokes. Remember to select a fill before you draw the pencil strokes.
Determines whether to keep the path selected after you draw it. This option is selected by default.
Edit Selected Paths
Determines whether or not you can change or merge a selected path when you are within a certain distance of it (specified with the next option).