An overview of neutron activation analysis (NAA) and some applications for this technique are provided. The fundamentals of the various methods of NAA (INAA, relative, k0, large sample, prompt gamma charge particles, cyclic, molecular and radiochemical NAA, gamma-gamma coincidence NAA) are discussed in order to describe the most important scientific and technical aspects. Several problems associated with the technique are pointed out and briefly discussed. Emphasis is laid on the advantages of this technique for the determination of trace elements in geological, biological and environmental samples as an alternative analytical technique where other methods would not be the best choice. The role of NAA in quality assurance and quality control is also described.