ABSTRACT — ITER is a unique scientific, technological, and industrial project being built in the south of France through a partnership involving the European Union, China, India, Japan, Korea, Russia, and the United States. Its primary objective is to demonstrate the scientific and technological feasibility of controlled magnetic fusion, producing significant fusion power amplification (10 times the power input to the plasma) with an output of up to 500 MW for 300 – 500 s. This paper will give an introduction to the concept of nuclear fusion in general and the “tokamak” approach to magnetic confinement in particular. The tokamak magnetic configuration has been chosen for ITER as it has the most mature experimental and theoretical basis of all magnetic confinement concepts. It relies on the capture of a gas with temperatures in excess of 100 million degrees in a vacuum chamber using ultra-high magnetic fields. In ITER, these are generated by some of the world’s largest superconducting magnets. This talk will provide an introduction into the fundamental concepts of nuclear fusion and magnetic confinement in particular and highlighting a few examples of scientific challenge. It will furthermore give an overview of the ITER design, its current status of construction and highlight some of its unique technical challenges and their solutions.