The layer of the Earth made up of solid rock is known as the lithosphere. This includes both the crust and the uppermost part of the mantle. The lithosphere is rigid and encompasses the continents and ocean basins, playing a crucial role in geological processes such as plate tectonics. It interacts with the underlying asthenosphere, allowing tectonic plates to move. Understanding the characteristics of the lithosphere is essential for studying earthquakes, volcanism, and the formation of geological features.