Kiteboarding - The Kite Control Bar

You have seen them on the water, and maybe on the snow as well; riders racing along and boosting into the air at will, able to travel in any direct, and across any terrain while being pulled by the force of a giant kite. Kite sports have quickly evolved in the last ten years to become the newest and fastest growing "extreme" sport. So how does it all work? What are these riders doing to control the massive kites, and how is it possible that a kiter can stand on the beach or walk around while still flying a kite that moments before boosted him forty feet into the air?