This lecture covers the physics and applications of magnetic resonance spectroscopy at the nanoliter and subnanoliter scale, including the overview of magnetic resonance, state-of-the-art techniques, and the research on NMR, ESR, and FMR. It delves into the molecular structure determination, spin sensitivity, and the main advantages and disadvantages of magnetic resonance. The presentation also discusses the spin sensitivity and concentration sensitivity in NMR and ESR, as well as the different systems and detectors used in this field. The lecture concludes with the state-of-the-art advancements in nanoliter and subnanoliter magnetic resonance, focusing on single chip NMR detectors, ESR detection methods, and the future outlook of the field.