​The development of friction in minerals and soils has advanced in stages. Unprecedented experimental and numerical tools available today allow the study of friction in minerals at the atomic scale and in soils at the particle level. Results from these investigatio ns render new insight that can be used to explain macroscale observations in soils (e.g., friction anisotropy and the correlation with plasticity) and to explore anomalous soil responses. Furthermore, this enhanced understanding can lead to the development of "engineered soils" where friction is a design parameter.