pt. 1. Formalism: description of spin polarization: Introduction -- Spin states and spin polarization -- Density operator, density matrix -- Rotations, angular dependence of the tensor moments -- pt. 2. Nuclear reactions. Description of nuclear reactions of particles with spin -- Partial wave expansion -- Charged-particle versus neutron-induced reactions -- pt. 3. Devices. Sources and targets of polarized H and D ions -- Polarization by optical pumping -- pt. 4. Methods. Production of polarization by other methods -- Measurement of polarization observables -- Polarimetry -- pt. 5. Applications. Medical applications -- "Polarized" fusion -- Outlook -- Index