The main component in the Earth's core is iron, making up about 80% of its mass. The core consists of two parts: the outer core, which is liquid, and the inner core, which is solid. This iron-rich core is believed to create the Earth's magnetic field through the movement of molten iron and the dynamo effect. The core is surrounded by the mantle and the crust, and its extreme temperatures and pressures are a result of the gravitational forces and radioactive decay of elements within the Earth.