Point-in-time recovery (PITR) in the context of computers involves systems whereby an administrator can restore or recover a set of data or a particular setting from a time in the past. Note for example Windows XP's capability to restore operating-system settings from a past date (before data corruption occurred, for example). Time Machine for Mac OS X provides another example of point-in-time recovery.
Once PITR logging starts for a PITR-capable database, a database administrator can restore that database from backups to the state that it had at any time since.
References
Point-in-time recovery Wikipedia(Text) CC BY-SA