The ITER design is based on objectives which were laid down at its inception and those which have evolved through its various design phases.

The main parameters of ITER are set by these objectives and by extrapolation from an independent comprehensive assessment and distillation of the knowledge base in experimental plasma physics worldwide.

The design of the ITER components and systems have been developed to various degrees of detail, according to the level of their final procurement with industry.

The existing materials database is used as far as possible, to ease licensing, but ITER component performance requires tight specifications of material composition, and a careful selection of material grades and preparations.