A data schema is a blueprint that defines the structure of a database. It outlines how data is organized, including the tables, fields, and relationships between them. This structure helps ensure that data is stored consistently and can be easily accessed and manipulated. In relational databases, a data schema typically includes details about data types, constraints, and keys. For example, a schema for a customer database might specify that the customer ID is a unique identifier, while the customer name field can hold text. This organization is crucial for efficient data management and retrieval.