Nuclear safety is the academic field and applied discipline focused on the prevention of accidents and the mitigation of risks associated with the design, construction, operation, and decommissioning of nuclear facilities, as well as the handling and storage of nuclear materials. It investigates the complex interactions between technology, human factors, and organizational structures to ensure the protection of personnel, the public, and the environment from the harmful effects of ionizing radiation and potential nuclear events. Key characteristics include a multidisciplinary approach integrating rigorous engineering, probabilistic and deterministic safety analysis, robust regulatory frameworks, and a pervasive safety culture, all aimed at achieving defense-in-depth. Its significance is paramount for the responsible and sustainable utilization of nuclear energy and technology.