Hatching (French: hachure) is an artistic technique used to create tonal or shading effects by drawing (or painting or scribing) closely spaced parallel lines.
Hatching is especially important in essentially linear media, such as drawing, and many forms of printmaking, such as engraving, etching and woodcut.
In Western art, hatching originated in the Middle Ages, and developed further into cross-hatching, especially in the old master prints of the fifteenth century.
Artists use the technique, varying the length, angle, closeness and other qualities of the lines, most commonly in drawing, linear painting and engraving.
The main concept is that the quantity, thickness and spacing of the lines will affect the brightness of the overall image and emphasize forms creating the illusion of volume.