This guidance document introduces the International Generic Sample Number (IGSN ID) as a persistent identifier (PID) for material samples, specimens, objects, sample aggregations, and other research outputs. It explains what IGSN IDs are, what they can be assigned to, how they support the identification, discovery, citation, linking, and reuse of samples, and how they are registered through DataCite services. The document also outlines practical considerations for organizations that want to integrate IGSN IDs into existing sample management systems, DOI registration workflows, metadata practices, and landing page services. The guidance has been developed in the context of the German National Research Data Infrastructure (Nationale Forschungsdateninfrastruktur, NFDI), which brings together research communities and institutions across Germany to improve the management, accessibility, interoperability, and reuse of research data across disciplines. It is primarily intended for NFDI-related organizations, DataCite community members, research institutions, repositories, data and information specialists, domain experts, and researchers who work with or manage material samples. It provides an entry point for understanding the benefits of IGSN ID adoption, the organizational requirements for registration, available service options, and the role of IGSN IDs in supporting FAIR, CARE, and Open Science principles.