1. Crust: This is the outermost layer, the one we live on. It is relatively thin and is made up of solid rock.

2. Mantle: This is the thickest layer, made up of mostly solid rock, but with a partially molten layer called the asthenosphere. It's where convection currents occur, driving plate tectonics.

3. Core: This is the Earth's center, composed of a solid inner core and a liquid outer core, both made mostly of iron and nickel.

Let me know if you want to know more about any of these layers!