Master data is the foundation of your business, supporting your core processes, connecting your operational systems, and enabling reliable decision-making. It underpins your transactional data, links to your reference data, and shapes your metadata. Without trusted, structured, and well-governed master data, even the most advanced analytics or automation efforts are built on unstable ground. This chapter introduces the critical concepts of master data governance (MDG) and master data management (MDM)—two disciplines that work hand in hand to ensure that your data is accurate, consistent, and usable throughout the organization.