Abstract: Due to the basic properties of neutrons, which carry zero charge but have nonzero magnetic moments, neutron scattering technology has become very important in condensed matter and material science. The zero charge allows neutrons to penetrate deeply into the sample, while the energies available at neutron scattering facilities are close to many excitation energy ranges in solids, corresponding to phonons in crystals, spin waves in ordered magnets, and so forth. In addition, magnetic neutron scattering shows significant differences in the spin liquid ground states where translational symmetry is not broken. These make neutron scattering well suited and unique for the study of magnetic order and spin-spin correlations, especially for the study of low dimensional and strongly frustrated quantum magnets. Here we will give a general introduction to inelastic neutron scattering. Recent research on the exotic spin excitations observed in rare-earth perovskites using inelastic neutron scattering will be discussed as well.