After presenting an overview of the geophysical constraints on the elastic structure and density of the Earth's interior, we will discuss the relevant elements which constitute the Earth's interior, starting from a brief summary of the origin of the Earth and cosmic abundances of elements to a comprehensive mineralogical description of the Earth's interior. Inside the Earth, temperatures and pressures can be become very high and profoundly affect the elastic properties and density of minerals. We give an overview of how to model the temperature and pressure dependence of the elastic properties of minerals. In the last part of course, we present a synthesised view of the Earth's interior which takes the geophysical, petrological and geochemical aspects we introduced into account.