This tutorial is part of WebPhysics, a site "devoted to teaching and learning physics with World Wide Web technology." The first lesson teaches visitors about orbital mechanics. The second and third lessons delve into the theory and science that make global positioning satellites a reality. Each of the three lessons contains sections on Exploration, Application, and Theory. The clearly articulated lesson objectives combined with the interactive exercises in the Exploration and Application sections are sure to make this site popular with students and teachers alike.