Two factors are critical for understanding silks: the nanoscale semicrystalline folding structure, which gives high strength as well as exceptional toughness and the degree of hydration of the disordered fraction, which modifies these material properties. The combination of these two factor allows for a massive range of mechanical properties. Understanding and controlling these two principal factors are the key to the functionality of protein elastomers, and render silk an ideal model protein for (bio)material design.