In this lesson, I learned about the Pencil Tool and its usefulness when creating paths.

The Pencil Tool inside of Illustrator is a freehand drawing tool. To start, head to the Pencil Tool in the Tools Panel and double-click, opening a box. Here you can change its fidelity, fill new pencil strokes, keep selected, toggle Option Key, and edit selected paths. There is also another option to determine whether or not the Pencil Tool will activate based upon an object.
To use the Pencil Tool, simply click and drag to create a freeform path. If you hold down Option, you can create a straight line segment. When holding down Shift, you constrain the path to 45 degree increments. Once you get back to the beginning of the path, the Pencil Tool will indicate to close the path.