Abstract
The paper reviews, at an introductory level, the theory of photon scattering from condensed matter. Magnetic scattering, which arises from first-order relativistic corrections to the Thomson scattering amplitude, is the main topic. A general theoretical framework is discussed for the cross section and secondary polarisation. Specific results of immediate interest are presented, including the case of circular polarisation of the incident and secondary beams. Use of the magnetic neutron and photon scattering techniques is also contrasted.