Thickness[r] is a graphics directive which specifies that lines which follow are to be drawn with a thickness r. The thickness r is given as a fraction of the total width of the graph.
Thickness can be used in both two- and three-dimensional graphics.
The initial default is Thickness[0.004] for two-dimensional graphics, and Thickness[0.001] for three-dimensional graphics
See Section 2.10.3.
See also: AbsoluteThickness, PointSize, Dashing, PlotStyle.
New in Version 1.