As an Element of Art, form connotes something that is three-dimensional and encloses volume, having length, width, and height, versus shape, which is two-dimensional, or flat. A circle becomes a sphere in three dimensions, a square becomes a cube, a triangle becomes a pyramid or cone.
What Sells Best On Shutterstock?
Some types of photos that sell best are Portrait Photography, Food Photography, Landscapes (usually with people) and fine art photography (artsy).