Earth's structure consists of four main layers: the crust, mantle, outer core, and inner core. The crust is the thin, solid outer layer where we live, while the mantle lies beneath it, made of semi-solid rock that flows slowly. Beneath the mantle, the outer core is a liquid layer composed mainly of iron and nickel, generating Earth's magnetic field. At the center is the inner core, a solid sphere of iron and nickel, with temperatures as high as 5,700 degrees Celsius. Together, these layers create the dynamic planet we inhabit.