Here's a breakdown of the Earth's layers:

* Crust: The outermost layer, thin and rocky.

* Mantle: The thickest layer, made of hot, dense rock.

* Outer Core: Liquid iron and nickel.

* Inner Core: Solid iron and nickel, incredibly dense and hot due to immense pressure.

The inner core is about 1,220 kilometers (758 miles) thick and sits at a depth of approximately 5,150 kilometers (3,200 miles) below the Earth's surface.