The lithosphere consists of the Earth's crust and upper mantle. It varies in thickness around the world, being thinner under oceans and thicker under continents. The lithosphere is broken into plates that move over time via convection currents in the underlying mantle. The Earth's crust differs in structure and thickness under oceans versus continents. Continental crust is thicker and composed of three layers, while oceanic crust is thinner and lacks a middle layer. The lithosphere displays properties of variability, heterogeneity, and anisotropy due to differences in its composition and structure across space and depth.