Book excerpt: Nanoindentation of Natural Materials: Hierarchical and Functionally Graded Microstructures provides a systematic introduction and review of state-of-the-art statistical hierarchical and functionally graded structures found in bone, teeth, hair, and scales, from a nanoindentation perspective, including detailed microstructure and composition. It covers the basics of hierarchical and functionally graded structures and nanoindentation techniques and detailed discussion with correlation micro/nano mechanical-structures The book includes practical issues backed with experimental data