Couchbase Server 5.0 introduces improved authentication and authorization features, including role-based access control (RBAC), which enables more secure management of users and buckets. The new feature allows administrators to create users with specific permissions to access particular buckets, replacing the old password-based approach. To use these features, developers must create a user and assign roles, then authenticate using a `PasswordAuthenticator` object before performing operations on the cluster. Authentication is successful when credentials are correct, but authorization checks are also applied to prevent unauthorized actions, such as executing N1QL queries. The new RBAC features make Couchbase a leader in document database security, offering more robust protection for sensitive data.