What is the general layering blueprint of a terrestrial planet's interior?

Metallic core, silicate mantle, and rock crust.

Although internal structures vary slightly among terrestrial planets, they universally adhere to a general blueprint involving distinct layering based on material density. At the center is the densest component, the metallic core, primarily composed of iron and nickel, which can be solid or molten depending on the planet. Surrounding this core is the extensive silicate mantle, representing the bulk of the planet's mass underneath the surface. Finally, the outermost layer is the crust, a relatively thin shell composed of rock. This stratification is a direct consequence of planetary differentiation, where heavier materials sink to the center and lighter materials rise to the exterior during the planet's early, hot, and molten phases.