The 1st layer is called the crust is deepest in areas with mountains. Here it can be 43 miles thick. Both the continental and the oceanic crusts are bonded to the mantle to form a layer known as the lithosphere.
The 2nd layer is called mantle. The mantle is the solid part of the earths interior. The mantle lies between the earths dense,super-heated core and its thin outer layer, the crust. The mantle is about 2900 kilometres (1802 miles) thick and makes up a whopping 84% of earths total volume.
The 3rd layer is the outer core. Earths outer core is a fluid layer about 2400 km thick and composed of mostly iron and nickel that lies above earths solid inner core and below the mantle. It's outer boundary lies 2890 km beneath Earths surface.
The 4th layer is the inner core. Earths inner core is the innermost geologic layer of the earth. It is primarily a solid ball with a radius of about 1220 kilometres, which is about 20% of the earths radius or 70% of the moons radius. There are no samples of the Earths core available for direct measurement, as there are for the Earths mantle.
The earths layers get hotter and hotter as it goes down so no one has ever made it to the bottom of the Earth because it gets too hot and you may pass away or injure yourself very badly if you attempt this.
By genius_chocolate and daring_date. This was joint work.