Every time a business sells a product, pays an employee, or places an order, it generates data. That data needs a home — a well‑organized database. But how do we decide which tables to create and how they talk to each other? That is exactly what this chapter is about. We will learn two powerful tools — UML class diagrams and the REA framework — that let you draw a clear blueprint of any business process, a blueprint that can be turned directly into a real database.