Magnetic resonance is a field that has expanded to a range of disciplines and applications, both in basic research and in its applications, and polarized targets have played an important role in this growth. This volume covers the range of disciplines required for understanding polarized targets, focusing in particular on the theoretical and technical developments made in dynamic nuclear polarization (DNP), NMR polarization measurement, high-power refrigeration, and magnet technology. Beyond particle and nuclear physics experiments, dynamically polarized nuclei have been used for experiments involving structural studies of biomolecules by neutron scattering and by NMR spectroscopy. Emerging applications in MRI are also benefiting from the sensitivity and contrast enhancements made possible by DNP or other hyperpolarization techniques. Topics are introduced theoretically using language and terminology suitable for scientists and advanced students from a range of disciplines, making this an accessible resource to this interdisciplinary field.