1. Crust: This is the outermost layer, and it's what we live on. It's relatively thin, ranging from about 3-50 km thick. The crust is divided into two types:

* Oceanic crust: Found under the oceans, it's thinner and denser than continental crust.

* Continental crust: Found under continents, it's thicker and less dense than oceanic crust.

2. Mantle: This is the thickest layer, extending from the base of the crust to about 2,900 km deep. The mantle is mostly solid rock, but it's very hot and behaves like a very viscous fluid over long periods. This is where the process of plate tectonics takes place.

3. Core: This is the Earth's innermost layer, extending from about 2,900 km to the center of the Earth at about 6,371 km. It's divided into two parts:

* Outer core: It's liquid and composed mostly of iron and nickel. The movement of this liquid metal generates the Earth's magnetic field.

* Inner core: It's solid and composed mostly of iron and nickel, but at immense pressure.

It's important to note that these are just the three main layers, and there are actually sub-layers within the mantle and core. For example, there's a transition zone within the mantle, and a solid inner core surrounded by a liquid outer core.