This chapter discusses Earth's structure and composition, minerals and rocks, and plate tectonics. It describes Earth's layered internal structure consisting of the core, mantle and crust. The core is made of iron and nickel, the mantle is solid but plastic, and the crust composition depends on if it is oceanic or continental. Minerals are the building blocks of rocks and the three main rock types are igneous, sedimentary, and metamorphic which form through volcanism, deposition of sediments, and changes induced by heat and pressure. Plate tectonics explains how the lithosphere is broken into plates that move relative to each other through processes like seafloor spreading and collisions at plate boundaries.