Controlling who can do what in your application is crucial, as this can lead to security risks and operational inefficiencies. Capella Columnar's Role-Based Access Control (RBAC) allows for the definition of roles and access permissions for various external tools, such as BI tools and REST APIs. This fine-grained control helps secure data and ensures that each user has the necessary permissions to perform their tasks without overstepping boundaries. By leveraging RBAC, users can create custom roles and assign specific privileges to manage data access securely.