AbstractScattering techniques (i.e. light scattering, X-ray scattering, or neutron scattering) are very powerful tools to gain insights into structural and thermodynamic properties of matter which often cannot be obtained by other methods. While classical thermodynamics is independent of length scale or applies for indefinitely long length scale, scattering can disclose thermodynamic properties like the free energy or free enthalpy as functions of length scale. Scattering is caused by density or composition fluctuations, which are functions of the length scale in one- or multicomponent systems. Therefore scattering techniques can give informations about the size, shape and molecular weight of scattering objects, their thermodynamic interactions with a surrounding matrix and their dynamics if correlations of the fluctuations as function of time are investigated (i.e. dynamic light scattering). As scattering techniques are less intuitive in comparison to complementary techniques, i.e. microscopic techniques, the aim of this article is to highlight some relevant relationships with a focus on polymer systems. This may encourage polymer scientists to consider the use of scattering techniques to learn more about the thermodynamics of their systems and/or to gain informations about their structural properties.