When you restore a database instance, you restore it to the last consistent state it was in before a system failure (such as a damaged hard disk). To do this, you need seamless data backups and log backups.
You can also restore a database instance to a state it was in at a point in time in the past.
See also:
· Concepts of the Database System, Backup and Recovery
· Database Manager GUI, Restoring Data
· Database Manager CLI, Recovering a Database Instance