It's been a long road but ITER has just passed the 50% milestone in building the new fusion reactor which might revolutionize the way electricity is being produced. Fusion reactor produces fusion power through fusion reaction which produces heat that can be used to further produce electricity. Basically the fusion reaction is the way how sun works.
Fusion power is a form of power generation in which energy is generated by using fusion reactions to produce heat for electricity generation. Fusion reactions fuse two lighter atomic nuclei to form a heavier nucleus, releasing energy. Devices designed to harness this energy are known as fusion reactors.
ITER is by far the most complex science project known in human history and the progress made so far is already a significant achievement.
More interesting information can be found from ITER's webpage:
https://www.iter.org/
Photo from http://www.sciencemag.org/