The Earth's Magnetic Field -- Basic Principles of Rock Magnetism -- Magnetic Prospecting -- Paleomagnetism -- Magnetic Fabric of Rocks -- Magnetic Signature of the Earth's Crust -- Magnetic Chronology -- Environmental Geomagnetism -- Historical Notes. This book reviews the general characteristics of the Earth's magnetic field and the magnetic properties of minerals, and then introduces the multifold applications of geomagnetism in Earth sciences. The authors analyze the contribution of geomagnetism both in general geological fields, such as tectonics and geodynamics, and in applied ones, such as prospecting and pollution. The book is designed to provide a general overview of geomagnetism, and an understanding of the contributions this branch of science makes in the specialized sectors of Earth sciences.