The line width control sets the width (thickness) of lines (and the outlines of other types of objects). If you change the value with objects selected, their line widths will change. If you change the value with no objects selected, the value you used will be set as a current attribute and used for all lines you draw in future. You can choose a value from the drop-down list or you can type a value and press RETURN. For more details, see Changing line thicknesses.

Changing line thickness

Units overview