The earth is made of 4 different layers that each has their own roles, the crust, the mantle, the outer core, and the inner core also known as the core.
The crust of the earth is the top layer and is only about 60 km thick. The crust is the rock layer upon which we live. Tectonic plates on top of the crust, are either giant plates of land or of water that fit together like puzzle pieces. When two tectonic plates rub against each other, a volcano pops up.
The mantle is the thickest section of the earth. Its thickness is 2,900 km and it is made out of magma. Magma is semi-molten rock.
The outer core is the layer surrounding the inner core. It is a barrier of liquid nickel and iron. It is liquid since it is close to the hottest part of the earth, the inner core.
The inner core is the hottest part of the earth and is the center. It is a solid mass of nickel and iron just like the outer core. The highest temperature the core can reach is 13,000 degrees Fahrenheit.
All of the layers of the earth surround the core guarding it relentlessly which might mean there is something important there. People never got to the core of the earth so they do not really know what is in there.