You can make objects partly or fully transparent, or even with a varying degree of transparency (as a gradient).
Suppose that you want to apply the same area fill, line thickness, and border to a set of objects. This repetitive process can be greatly simplified by the use of styles. Styles allow you to define a formatting template (a style) and then to apply that style to multiple objects. For more about styles, see Chapter 3 (Using Styles and Templates) for more information.