This is my contribution to the excellent OTN Appreciation Day idea by Tim
For example retrieving the value of the Employees salary as it was 10 minutes ago:
SQL> select sal from emp as of timestamp sysdate - interval '10' minutes where ename = 'SCOTT';
This feature can be used almost everywhere Oracle is used, for example it’s embedded into the Export Application feature of Oracle Application Express
As an extension to this, using the Flashback Data Archive feature allows you maintain an archive of your application data that you can query in real time – without having to write your own logic.
Flashback – an extremely useful but often little known and underused feature of Oracle!