3 CFU – Giuseppe AllodiDescription: The lectures provide an introduction to the basic principles of muon spin rotation (muSR) and nuclear magnetic resonance(NMR/NQR) applied to condensed matter in the presence of strong hyperfine and quadrupolar couplings of nuclei. The common aspects to the two experimental techniques, as well as their different scopes, are stressed. Their actual application to the study of magnetic order, spin excitations and phase transitions in magnetic materials, and of the superconducting order parameter in superconductors, is illustrated in some detail. The peculiar employment of muons as dilute hydrogen-like impurities in semiconductors, whose electronic and transport properties may be uniquely probed by the muon spin, is also presented.