Study of the Earth’s interior is an inter-disciplinary endeavor and a multitude of constraints from various fields are required to derive complementary information on Earth structure. Geochemists analyze rocks to provide constraints on the current and early composition of the mantle while mineral physicists estimate the physical properties of the rocks at high pressures and temperatures; geodynamicists model long-term deformation processes associated with the evolution of the mantle while geodesists monitor the motions on the Earth’s surface at shorter time-scales. Till date, seismology holds the distinction of providing the most uniform constraints on structure as the various types of seismic waves recorded on a global network of stations illuminate different regions of the Earth. I analyze and model seismic data along with observations from other fields in the geosciences to decipher the inner workings of our planet.