The Stroke Width Tool lets you edit the pressure profile of curves created with line tools, typically the Pencil Tool, but also the Pen Tool and Vector Brush Tool.
The tool lets you add or edit pressure points on a curve by clicking or moving them on the curve. At any selected point you can set the stroke width which, along with other points, forms the pressure profile along the curve's length; the stroke width is set by dragging a point's handle inwards (or outwards).
The following settings can be adjusted from the context toolbar:
These options are independent of the global snapping options.