For me sketching serves many purposes. First and foremost it is a way to visualize, ideate, and rapidly communicate the ideas that I have in my head. It also serves as a first reality check for many of my thoughts and hunches. From there it becomes a way to develop, sell, and explain an idea.
Below are some excerpts from my sketchbook they range quick and dirty sketches to get idea out of my head and begin to pick them apart to more developed presentable sketches