This document describes the core concepts of ISO/IEC 20000 (all parts), identifying how the different parts support ISO/IEC 20000‑1:2018 as well as the relationships between ISO/IEC 20000-1 and other International Standards and Technical Reports. This document also includes the terminology used in all parts of ISO/IEC 20000, so that organizations and individuals can interpret the concepts correctly. This document can be used by: a) organizations seeking to understand the terms and definitions to support the use of ISO/IEC 20000 (all parts); b) organizations looking for guidance on how to use the different parts of ISO/IEC 20000 to achieve their goal; c) organizations that wish to understand how ISO/IEC 20000 (all parts) can be used in combination with other International Standards; d) practitioners, auditors and other parties who wish to gain an understanding of ISO/IEC 20000 (all parts).