Line art or line drawing is any image that consists of distinct straight or curved lines placed against a (usually plain) background, without gradations in shade (darkness) or hue (color) to represent two-dimensional or three-dimensional objects. Line art can use lines of different colors, although line art is usually monochromatic. Line art emphasizes form and outline, over color, shading, and texture. However, areas of solid pigment and dots can also be used in addition to lines. The lines in a piece of line art may be all of a constant width (as in some pencil drawings), of several (few) constant widths (as in technical illustrations), or of freely varying widths(as in brush work or engraving).