1. Crust: This is the outermost layer, the one we live on. It's thin compared to the other layers, and it's divided into oceanic crust (thinner and denser) and continental crust (thicker and less dense).

2. Mantle: This is the thickest layer, made up of mostly solid rock but with a semi-molten layer called the asthenosphere. The movement of the mantle drives plate tectonics.

3. Core: This is the innermost layer, divided into a solid inner core and a liquid outer core. The outer core generates Earth's magnetic field.