This report aims at providing background information and a comprehensive account of the nature of nuclear geophysics, its fundamentals, its objectives, its tools for investigation and its wide range of applications benefiting society and industry. It reviews the achievements and performance of nuclear geophysical measurements, particularly in applications to mining, industry and agriculture. It also analyses many of these important applications for their economic impact and updates the available information on nuclear geophysics by giving an account of the most relevant achievements and concepts introduced during recent years. Contents: 1. Introduction; 2. Fundamentals of nuclear physics; 3. Parameters obtained by nuclear techniques; 4. Measurement methods; 5. Interpretation; 6. Impact of new technology.