Line art is any image that consists of distinct straight and 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).
Before the development of photography and of halftones, line art was the standard format for illustrations to be used in print publications, using black ink on white paper. Using either stippling or hatching, shades of gray could also be simulated.
See also: Etching.
In the pen and ink technique, a pointed still tipped pen is dipped in an ink bottle to draw fine lines on paper. A style appearing not unlike that produced by quality etching is common. Line width is usually constant, using instead a greater number of strokes per unit area to give density to a region of the piece. Use of cross-hatching to imply shadow or texture is common. Large areas are frequently filled in with many short closely-space parallel lines to imply darkness. Edward Gorey is a writer/artist noted for his use of this technique.
Like pen and ink, (Western) calligraphy uses pen and ink. In this technique, however, the tip of the pen is broad and flat-tipped, giving rise to different stroke-widths depending on the direction in which the pen is travelling.
To this very broad category of pencils and pens, are relegated all of the school-house-scribblings, cartoons, diagrams, penmanship, and fine-art which are characterized generally by monochromatic lines of constant-width on paper, body parts, plaster casts, and restaurant napkins (during lunch-time Eureka-moments).