The Create Polyline Tool lets you draw straight polylines or lines. To start, click on the spot where you want the first point to be located, then click again on the spot where you would like to put the next point, and so on. To finish creating the line, either double-click when creating the last point, press the "Finish" button on the toolbar, or simply switch to a different tool.

Preset: Specifies the preset of an envelope to put around the newly drawn polyline.
Finish: Pressing this button finishes creating the current line.