Orbital motion is a vital subject which has engaged the greatest minds in mathematics and physics from Kepler to Einstein. It has gained in importance in the space age and touches every scientist in any field of space science. Still, there is almost a total dearth of books in this important field at the elementary and intermediate levels — at best a chapter in an undergraduate or graduate mechanics course.This book addresses that need, beginning with Kepler's laws of planetary motion followed by Newton's law of gravitation. Average and extremum values of dynamical variables are treated and the central force problem is formally discussed. The planetary problem in Cartesian and complex coordinates is tackled and examples of Keplerian motion in the solar system are also considered. The final part of the book is devoted to the motion of artificial Earth satellites and the modifications of their orbits by perturbing forces of various kinds.