In nanomaterials, a large fraction of atoms is directly exposed to the surface. Nanochemistry therefore benefits enormously from established experience in surface science. The lower coordination number of atoms at corners, edges and in the middle of surfaces is a direct measure of the degree of unsaturation of these atoms and therefore of their energetic stabilisation and their desire to form chemical bonds, e.g. in catalytic reactions. The strategy of building a rich variety of tiny, stable or metastable, reproducible structures at room temperature is inspired by the way nature has done this for thousands of years. Important mechanisms are self-assembly and template-directed synthesis.