Scientists have long pursued the harnessing of controlled nuclear fusion for energy production. The potential for fusion to, in principle, generate vast amounts of energy from relatively plentiful fuel with few by-products has made it an ideal source for large-scale energy production in the future. All of this relies first and fore-most on finding a method of controlling, sustaining, and scaling up a fusion reaction, all of which are non-trivial engineering and nuclear physics challenges. One method that has been pursued towards achieving these goals is the use of powerful magnetic fields to confine a superheated torus of plasma within a device broadly known as a tokamak.  The current cutting edge of this research is represented by the International Thermonuclear Experimental Reactor, ITER, a massive tokamak currently being constructed in Southern France.
ITER is a joint project between the EU, United States, Japan, India, Russia, China, and South Korea with the goal of constructing a tokamak that can use the deuterium-tritium reaction, shown below, to generate a fusion reaction characterized by a value of Q, the ratio of the output power to the input power, of at least 10. To get to this level, the ITER is planned to generate 500 MW of power using an input of 50 MW, which is spent on heating the plasma and maintaining the magnetic fields.  ITER is built off of the experiences of smaller tokamaks built by smaller organizations including the JET (Joint European Torus) and TRIAM-1M, built in Japan.
The progress of a reactor towards generating sustained nuclear fusion can be empirically assessed by the triple product of the density, temperature, and confinement time which is related to the rate of energy loss. This product can be compared with the theoretical Lawson criterion for igniting a fusion reaction to assess the progress made towards a sustained reaction. For the D-T reaction shown above, the triple product needs to exceed 3 ×1021 keV s/m3, which has yet to be achieved. The team behind ITER has set a target of reaching 5.4 ×1021 keV s/m3. This value can be directly compared to the peak performance of one of ITER's predecessors, the JT-60U, of only 1.5 × 1021 keV s/m3. [1,3] The ITER is set to generate plasma with properties that have yet to be explored in terrestrial facilities, paving the way for future research.
Construction on ITER has only recently begun in earnest in 2007. Since then, work has only been focused on the foundation and support facilities for the main experiment, with construction of the tokamak facility not planned until mid-2013. After that, construction and assembly will still take another 7 years before the first plasma experiments can begin, assuming all goes according to plan. One recent milestone that has been passed is that the French government has given authorization for the construction of the nuclear facilities to begin. This shows that the project has the full support of the local government and that they have faith in the safety and potential of the project. This precludes future intervention by the government, a possibility given the strong anti-nuclear backlash following the Fukushima disaster in Japan. [3,4]
The ITER project has also attracted its share of criticism which points at its exorbitant cost, the potential for better use of the ITER funding, potential safety issues due to the unproven stability of the reactor itself, and the lack of a direct link between ITER and electricity generation.  This last point is an uncomfortable truth of the project since there are no plans to directly implement ITER for power generation, as the complex is purely experimental. ITER is designed only to judge the practicality of scaling up fusion reactions and the real effects of sustaining a reaction on the tokamak itself. Because of this, the ITER project cannot be thought of as an immediate solution to the energy crisis or as a source of sustainable energy, even in a very successful outcome, for at least 30-40 years.
As part of a bigger picture, ITER itself is planned to serve as stepping stone towards actual power generation. As mentioned earlier, ITER is designed as the successor to projects such as JET, but it is also meant to bridge smaller research focused projects such as JET and actual power operation, which is represented by the planned construction of DEMO (The DEMOnstration power plant). Construction of DEMO is planned to begin parallel to the first plasma operations of ITER, in 2020, and the proposed date for finishing DEMO is 2030. DEMO is planned to generate 2-4 GW of power, of which ~1 GW will be converted into electricity. It should be stressed that all of this is contingent on successful operation of ITER and should any of that project fail, the chances of these numbers becoming reality will substantially decrease. 
© Zach Herrera. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 J. Kates-Harbeck, "Magnetic Nuclear Fusion," Physics 240, Stanford University, Fall 2010.
 R. Aymar, et al., "The ITER Design," Plasma Phys. Control. Fusion 44, 519 (2002).
 K. Ikeda, "ITER on the Road to Energy Fusion," Nucl. Fusion 50, 14002 (2010).
 "Decree 2012-1248," Government of France, Minister of Ecology, 10 Nov 12.
 L. Hickman, "Fusion Power: Is It Getting Any Closer?" The Guardian, 23 Aug 11.