 Providing energy from nuclear fusion is widely regarded as the grand engineering challenge of the 21st century. Unlike fission, where the atom is split to produce energy, in fusion, two lighter atomic nuclei emerge to form a heavier nucleus. This is how stars transmute matter into energy, and this is the main goal of plasma physics research. An international experimental fusion reactor under construction in France, ETA, is aimed at demonstrating that fusion power can generate energy. The IAEA has played a key role for ETA's creation and its endeavors. To make fusion power commercially viable, a number of serious technological challenges will have to be overcome. A plasma with temperatures exceeding 100 million degrees Celsius, 10 times higher than in the core of the sun, has to be confined and controlled using the largest magnetic fields ever produced. Finding the right materials and the mechanism that will extract and convert the enormous amount of energy are also among the major challenges in producing electricity from fusion. Through various international cooperation activities, the IAEA promotes innovation that leads to more efficient and affordable nuclear technologies.