The past 20 years of condensed matter physics can be savely coined the age of spin-orbit physics. The energetically tiny spin-orbit interaction, in combination with certain crystal symmetries, can produce huge emergent internal wave-vector-dependent magnetic fields, angular momentum flow and topologically non-trivial wavefunction properties with important ramifications for the spin-polarization of the electronic structure in nonmagnetic solids, the creation of topological matter, spin relaxation and generation phenomena of spin-currents, longitudinal and transversal electron transport properties and the magnetic interactions (e.g., single- and two-ion magnetic anisotropies, Kitaev, Dzyaloshinskii-Moriya) in magnets, the former making magnets the second most important commercially important materials class and the latter being the interactions stabilizing topologically protected, nanoscale, two-dimensional magnetization textures such as chiral skyrmions, which are thought to be novel entities for information technology. Density functional theory has proven to be very powerful in extracting these properties. Accordingly, many community electronic structure codes based on density functional theory (DFT) and even methods implementing many-body perturbation theory in terms of Hedin's GW approximation of the self-energy included the spin-orbit interaction non-self-consistently and self-consistently in first and second variation on top of the scalar-relativistic approximation. In my presentation, I briefly comment on typical implementations of the spin-orbit coupling in electronic structure methods using DFT and discuss the different methodologies to determine the spin- and orbital moments, and the magnetic interactions that arise from the spin-orbit coupling and trace those back to the changes of the electronic structure. The underlying approximations are discussed. Some examples are given.