Radiotracers and radioisotope sealed sources have been widely used, as a unique diagnose tool without requiring the shutdown, in various industries to optimize processes, troubleshooting, improve product quality, save energy and reduce pollution release.Through the efforts of IAEA activities mentioned, among others, in this e-learning tool, substantial development of industrial and environmental radiotracers and sealed sources applications has been achieved and many important applications have been transferred to developing countries.The purpose of this e-learning tool is to enhance and consolidate both developing and developed member states capability in online industrial process diagnosis, optimization and troubleshooting, using radiotracers and sealed source techniques.This tool is an output of a collaborative work between NAPC and TC through the Regional Project RER1020 "Developing Radiotracer Techniques and Nuclear Control Systems for the Protection and Sustainable Management of Natural Resources and Ecosystems"?? ??? ? ???