Questions about inital design roughs. A sketch a is not meant to be the end result of a design or piece of art. It is a quick, often conceptual outline to demonstrate an idea, shape or process.
Sketching is often done on paper, freehand, but it is more and more common to do it digitally. Sometimes as collages of elements to get a basic idea or principle across. Sketching can be a very powerful and effective way of visually communicate ideas.
Sketching can also be done in 3D mediums.