This document defines the terms which are used in the ISO 21111 series and provides an overview of the standards for in-vehicle Ethernet including the complementary relations to ISO/IEC/IEEE 8802‑3:2017^[7] and its amendments, the document structure in accordance with OSI reference model specified in ISO/IEC 7498‑1^[1] and ISO/IEC 10731:1994,^[2] type of physical entities, in-vehicle Ethernet specific functionalities, and so on.