Magnetic resonance (MR) makes use of tiny radio signals emitted by the nucleus of the atom. There are two important applications - chemistry, where MR allows us to visualise the architecture of molecules, and medicine, where it provides a clear picture of human anatomy without the need for invasive surgery. This is the first unified treatment of Nuclear Magnetic Resonance (NMR) in chemistry and Magnetic Resonance Imaging (MRI) in medicine, written for a broad non-specialistreadership by one of the worlds foremost NMR spectroscopists.