As mentioned before, we can query the content of a table from the past (since 9i with flashback query) and even reinstate the past content of that table (since 10g with flashback table to timestamp) by making additional use of before images stored in the undo tablespace. Of course, this is only possible as long as these before images in the undo tablespace are not overwritten by new ones.
A new feature of the 11g version is to safe the information from the before images for selected tables, thereby enabling a flashback query or flashback table to timestamp for these selected tables even years after their modification. That is called Total Recall and works like this:
SQL> create flashback archive fla1 tablespace tbs1 retention 10 year;
SQL> alter table hr.departments flashback archive fla1;
You will now be able to do a flashback query for the departments table in 10 years until today and to any time in between!