The terms for describing advanced nuclear power plants (NPPs) need to conform to the broad, general, common understanding by the public as well as by the technical community. This publication is a revision of IAEA-TECDOC-936 incorporating developments and initiatives since 1997 in the areas of advanced, evolutionary, and innovative nuclear reactor designs, description of design development phases, inclusive of relevant safety and regulatory terminology, consistent with current IAEA safety standards and glossaries. The objective of this publication is to provide Member States with up-to-date terms for describing advanced NPPs, to draw distinctions between design phases reflecting the maturities of designs, and to clarify definitions of commonly used terms in describing advanced NPPs