ITER is a project involving 35 nations to build the largest tokamak in the world located in the south of France. Tokamak is a machine for producing a toroidal magnetic field for plasma delimitation, and devices of this type are collectively called fusion reactors. The reactor produces heat, that heat of steam that drives the turbines, and so it produces electricity. The machine works on the same principle on which the Sun and stars receive energy. Nuclear fusion began to be explored after World War II, and in the 1950s, Tokamak was invented by Soviet physicists. Soviet scientists constructed the first tokamak, and the largest version was tested in 1968 in Novosibirsk where they reached electron temperatures of over 1,000 electron volts. Experimental research to be conducted at ITER is crucial for fusion science in progress and preparations for the development of future fusion power plants. This is also the goal of the ITER project, to make the transition from experimental studies to power plants with full production capacity. The ITER fusion reactor is designed to produce 500 megawatts of output power with 50 megawatts of input power, ie to produce 10 times more energy, in research projects so far this has not been the case, ie the output power has always been less than invested. Construction began in 2007, and when ITER becomes operational, it will become the largest experiment in the physics of magnetic plasma trapping. A team of scientists from the Hefei Institute of Physics in China say the older reactor design is also usable, claiming they created hydrogen plasma at a temperature of about 50 million degrees Celsius, and maintained it for 102 seconds. If this success is confirmed, it will be the longest constant fusion reaction.