A robust Common Service Data Model (CSDM) Foundation is essential for organizations seeking to maximize the value of their ServiceNow platform. Foundation Data underpins all Configuration Management Database (CMDB) and CSDM building blocks, enabling efficient service delivery, accurate reporting, and effective governance. This guide provides best practices, lessons learned, and answers to common questions, drawing on ServiceNow product guidance, industry experience, and insights from the Certified Implementation Specialist – Data Foundations (CMDB & CSDM) certification.