The world’s largest tokamak, ITER, is being built in Cadarache, France. It is designed to generate 500 MW of fusion power from 50 MW of external plasma heating power, corresponding to Q ≥ 10. ITER is a joint project of China, the EU, India, Japan, Korea, Russia, and the USA. The device has a plasma volume of 840 m³ and toroidal magnetic coils 17 metres high. It will test tritium breeding concepts along with a number of other technologies. Research operation is expected to start in 2034, with deuterium-tritium operation planned for 2039. Knowledge gained from experiments on ITER should provide important data for the development of demonstration fusion power plants that will generate electricity.