This book is about the technologies that comprise the field of commercial satellite communication, intending to provide a bridge between those who need a practical understanding and those whose business it is to develop and operate theses systems. One of the main objectives of the book is to give the reader enough understanding to allow him or her to ask the right questions. The explanations and factual material provided here are directed toward that objective rather than offering a technical or historical reference. All of the primary areas of satellite communications are covered in relevant chapters. Technical concepts are introduced as need, without using detailed design information. It is hoped that this will keep the reader from getting lost in the "forest" of engineering equations and complicated diagrams that are found in other technically oriented text books and manuals.