Earth has several layers. We live on the crust: the outer, rigid layer called the lithosphere, which includes both the continents and the ocean basins.
Beneath the crust lies a very hot, partly molten section known as the mantle. The uppermost section of the mantle is called the asthenosphere, and is plastic, or flexible. It is about 100 miles (160 kilometers) thick and is composed of molten rock, or magma.
Below that, the rock is solid again because the pressure consolidates molten rock and liquids into hard rock and other solids.
Deep within Earth lies the core, which has two distinct layers. The outer core is liquid and contains iron, nickel, and various other metals. The inner core is a solid ball of iron and nickel 1,500 miles (2,400 kilometers) in diameter.