This document discusses the design and properties of superhard nanocomposite coatings. It explains that nanocomposite coatings contain at least two phases and can achieve hardness above 40 GPa. The document outlines various design methods for nanocomposite coatings to achieve high hardness and toughness, including using a combination of nanocrystalline phases within a matrix and modifying interface complexity. It also describes common synthesis and deposition techniques like magnetron sputtering and chemical vapor deposition, as well as methods for evaluating the mechanical properties of nanocomposite coatings, such as nanoindentation and measuring adhesion.