Schema Definition refers to the formal structure that defines how data is organized within a database. It outlines the relationships between different data elements, including tables, fields, and data types. This structure helps ensure data integrity and consistency, making it easier to manage and retrieve information. In the context of databases, a schema serves as a blueprint for how data is stored and accessed. It can include constraints, such as primary keys and foreign keys, which enforce rules on the data. Overall, a well-defined schema is crucial for effective database design and operation.