Nuclear physics is a rich and active field. The large amounts of latent energy within the nuclei of atoms can be liberated in nuclear reactors. Together with nuclear weapons, this is the most familiar application of nuclear physics, but ‘Applied nuclear physics’ provides a summary of other applications to industry, medical science, and human health. The phenomenon of natural radioactivity provides beams of particles, which may be used to initiate other nuclear reactions, or to attack tumours in cancer treatment. Forensics via induced radioactivity, nuclear magnetic resonance imaging (NMRI), and positron emission tomography (PET) scans are also described.