The inner core of the Earth is composed primarily of solid iron and nickel. It is the innermost layer of the Earth, located about 3,200 to 3,600 miles beneath the Earth's surface. Despite the extreme temperatures, estimated to be as hot as the surface of the sun, the inner core remains solid due to the immense pressure at that depth.

Surrounding the inner core is the outer core, which is also composed of iron and nickel but exists in a liquid state. The inner core plays a crucial role in generating the Earth's magnetic field through the movement of the liquid outer core around it.