Small-angle scattering of X-rays (SAXS) and neutrons (SANS) is an established method for the structural characterization of biological objects in a broad size range from individual macromolecules (proteins, nucleic acids, lipids) to large macromolecular complexes. SAXS/SANS is complementary to the high resolution methods of X-ray crystallography and nuclear magnetic resonance, allowing for hybrid modeling and also accounting for available biophysical and biochemical data. Quantitative characterization of flexible macromolecular systems and mixtures has recently become possible. SAXS/SANS...