In database systems, particularly those that use transactions, a commit operation is necessary to make any changes made during a session permanent, or 'persistent'. This process ensures that once a transaction is committed, the changes made to the database are saved in a way that they will be available in subsequent sessions, even if the database system restarts or experiences a failure. If a commit is not performed, the changes remain temporary and can be lost when the session ends, which is why the statement given is true.