The Pencil tool is your basic drawing tool. You can draw in different colors, but other than that there are no other options. The pencil’s stroke is a single pixel wide, which makes it useful for working with fine details, but a poor choice for filling in large areas of the image with color.

Example:

  You can do simple line drawings with the pencil if you have the coordination to guide the mouse with great care.

Tip:  To draw straight lines, hold down the Shift key as you draw with the pencil.  Your pencil line will be limited to horizontal, vertical, or a 45-degree diagonal.