This course examines the scientific fundamentals of navigation systems and their use in the guidance of machines and humans. The course is of particular relevance in military applications. However, it is developed from the point of view of the scientific principles involved, and their applications in the military, civilian and research environments. All navigation systems require accurate time-keeping capability, coordinate reference definition, and information coding, transmission and interpretation. These concepts are examined in the areas of celestial navigation, underwater navigation, and old and new satellite-based navigation, including a detailed study of GPS systems. Inertial navigation and guidance is of primary importance in aircraft and weapon guidance. The science of inertial navigation systems is studied. Finally, the techniques involved in integrating inertial, celestial and GPS systems to produce state-of-the-art navigation and guidance capability are discussed.