A broad-spectrum review of the applications of electron spin resonance to advanced materials is presented. Starting with basic concepts the reader is taken through a quick tour of techniques including continuous-wave and pulse ESR, microscopy and imaging, as well as a few emerging techniques. Applications of spin identification, spin counting, spin mapping and spin imaging of a variety of advanced solid state materials including metals and alloys, semiconductors, inorganics, electroceramics, catalysts, intercalates, polymers, glasses, and organic charge-transfer complexes besides superionic conductors and high-temperature superconductors are included. It is thus demonstrated that the technique is at once specific, sensitive to composition, phase and texture yet accurate enough to be a quantitative but non-invasive tool that promises to be useful in the study of newer and newer materials including multilayers, ferrofluids and nanomaterials.