Texture is how a surface feels, or looks as if it would feel: furry, rough, smooth, grainy. In a drawing, texture comes from two things: the kind of mark you make, and the pattern of light and dark. You already have the marks from Cross-Hatching and Stippling.
Key idea
Match the mark to the surface (short strokes for fur, long wavy lines for wood, dots for sand, crisp broken darks for rough stone) and show texture most where light grazes the surface.
Why it works
A rough surface is a field of tiny bumps. When light skims across it from the side, each bump gets a lit side and a tiny shadow, so the texture shows strongly. Where the light hits straight on, or where the surface is in shadow, those tiny shadows disappear and the texture fades. Far away, the bumps are too small to see at all.
Worked example: Drawing a tree trunk
How do you draw the rough bark of a tree trunk lit from the left?
- Use broken, vertical marks with small dark cracks.
- Show the crisp bark pattern most along the edge where the light meets the shadow.
- On the lit side, keep marks light and sparse; in the deep shadow, let the bark merge into a darker tone.
Answer: Broken vertical marks, strongest where light meets shadow, fading in the full light and the deep shadow.
Common mistake
People draw texture evenly over every part, like wallpaper. The object then looks flat and busy. Put the most texture where light grazes the surface and in the front, and let it fade in the light, in the shadow and in the distance.
Dürer's watercolor Young Hare shows how fur works: strokes follow the direction the fur grows, and the texture is strongest where light catches it.