Shade and shadow are the two terms often heard in the art world. If you want to create a pencil drawing of something, then you would then shade the areas to show light and dark and give the picture some depth and make the items in the picture seem three dimensional. However, you can also shadow items where it looks like the item has cast a shadow on the ground or flat surface behind the item.
The sun or some form of light would need to be considered in front of the item in order for the shadow to be cast. Another similar definition of shadow is not used with art, but if you go outside, you can cast a shadow from the sun onto a sidewalk.