1. Crust: This is the outermost and thinnest layer, composed of solid rock. It is divided into two types: oceanic crust (found beneath the oceans) and continental crust (found beneath the continents).

2. Mantle: This is the thickest layer, located between the crust and the core. It is made up of hot, dense rock that flows slowly over time. The mantle is responsible for plate tectonics.

3. Outer Core: This is a liquid layer composed mostly of iron and nickel. The movement of the outer core generates Earth's magnetic field.

4. Inner Core: This is a solid ball of iron and nickel, despite the intense heat. It is incredibly dense due to the immense pressure from the layers above.

Let me know if you'd like to know more about any of these layers!