This document defines assurance-related terms and establishes an organized set of concepts and relationships to establish a basis for shared understanding across user communities for assurance. It provides information to users of the other parts of this document including the combined use of multiple parts. The essential concept introduced by this document (all parts) is the statement of claims in an assurance case and the support of those claims through argumentation and evidence. These claims are in the context of assurance for properties of systems and software within life cycle processes for the system or software product. Assurance for a service being operated and managed on an ongoing basis is not covered in this document (all parts).