Pencil Tool
With the Pencil Tool ( P or F6 ), the Inkscape artist creates freehand paths by drawing directly on the canvas in the desired curves. Inkscape evaluates the line or shape drawn by the user and produces nodes to form the path. After the path is drawn, the nodes of the path can be edited with the Node Tool, like other paths.
How to use
Choose the Pencil Tool, then click and drag the mouse to draw the line. By default it has no fill, but this can be set by any means (swatch or Fill and Stroke dialog). The line can also be set with stroke properties and colors in the Fill and Stroke dialog.
It is possible to close the line drawn while returning towards the initial point. When the mouse is close to this point, the point changes color to red to specify that a release of the mouse at this moment closes the shape.
Tips
These tools can create single dots by Ctrl + click on the canvas. This creates a small circle filled with the current stroke color. The radius can be set in the Preferences of the respective tools (it is specified as a multiple of the current stroke width). Shift + Ctrl + click creates a dot twice the specified size, and Alt + Ctrl + click varies the size of the created dots randomly.