A short remark on the terminology is given to avoid misinterpretation. “Satellite-based navigation” means navigation based on satellites, i.e., using signals transmitted by satellites. Quite often, this full nomenclature is shortened to the expression “satellite navigation”. This could be misleading because the navigation of satellites could be associated. Primarily, this book implies satellite-based navigation and the authors tried to use the correct denotation. Frequently, the term global navigation satellite system (GNSS) is used to refer to the current global systems.