I mentioned neutron scattering (or in particular, inelastic neutron scattering) as being one of the most important experimental technique in studying the magnetic properties of matter. This is true if the material has some ordered magnetism. This technique has been used to show the ordered magnetic phase separation in high-Tc superconductors, an observation that some have used to promote the stripes model. This is a good and condensed overview of what can be known using neutron scattering technique. It pays particular attention to some of the work done on high-Tc cuprates. Zz.