Shadows are important in graphic design for two key reasons. First, they create dimensionality, giving your images a deeper, richer look and feel. Second, they create the illusion of layers, helping the reader or viewer prioritize and organize content. But building shadows correctly is both an art and a science. Jan White, in his new book, Editing by Design, offers these five tips for doing it well.

1.  Watch the light source. Although shadows can be placed anywhere, since the imaginary light source creating your shadow can be placed anywhere, it’s best to stay with the tried and true. Most graphics use shadows resulting from an imagined light source placed 45-degrees above the top left corner of the figure, with the shadow falling below. Other placements can help bolster other design ideas, however. For example, placing the light source below the object can create a spookier feeling, much like placing a flashlight below your face.

2.  Watch the width. The width of the shadow is actually dependent upon concrete factors and shouldn’t be left up to a whim. For example, the width depends on the distance between the object and the surface on which its shadow is cast. A good rule of thumb, White says, is "the greater the distance, the larger the shadow."

3.  Go for variety. It’s best to avoid the one-dimensional look. Don’t have all the shadows cast by a variety of objects fall in the same way and have the same depth. Variety is key.

4.  Darkness adds dimension. The darkness of a shadow also depends on the distance between the object and the surface on which it is cast. The closer the object, the darker the shadow.

5.  Ramp from light to dark. This gradient in color lends to more realistic shadowing, adding texture as you gradually darken the shadow.