1. Crust: This is the thin, rocky outer layer of the Earth, where we live. It's divided into oceanic crust (thinner and denser) and continental crust (thicker and less dense).

2. Mantle: This is a thick layer of hot, dense rock that makes up the majority of Earth's volume. It's mostly solid, but can behave like a very viscous fluid over long periods.

3. Core: This is the Earth's innermost layer, composed mostly of iron and nickel. It's divided into the outer core (liquid) and the inner core (solid).