Most geological phenomena that have their expression on Earth's surface are triggered by processes in the deeper parts of the crust and mantle ie the so-called lithosphere that forms the uppermost 100 km of our solid, but dynamic planet. Rock and mineral transformation and reaction processes, involving also melting, deformation and migration of fluids within the lithosphere, are responsible for volcanic eruptions, earthquake generation and mountain building as well as the formation of ore deposits. Metamorphism - pressure- and temperature-induced changes in rock mineralogy and microstructure - is the major driving force for the subduction of oceanic lithosphere and thus influences the style and intensity of global plate tectonics, which in turn controls mountain building processes, surface erosion and basin development. Knowledge about the interplay between rock deformation, metamorphism, fluid migration and melt generation in the interior of the lithosphere is thus a key to a full understanding of large scale surface processes. Magmatic and metamorphic petrology investigates these complex processes at lithosphere scale by studying the temporal physical, chemical and kinetic behavior of rocks, minerals, melts and fluids during their history.