Earth's interior is composed of several layers, each with distinct properties. The outermost layer is the crust, which is solid and relatively thin. Beneath the crust lies the mantle, a thick layer of semi-solid rock that flows slowly over time. At the center of the Earth is the core, which consists of two parts: the outer core, made of liquid iron and nickel, and the inner core, a solid ball of iron. These layers play a crucial role in geological processes, including plate tectonics and the generation of Earth's magnetic field.