A good backup and recovery strategy is a must for anyone managing a database, of any type! You can recreate the database from scratch. And you can reconfigure and reinstall software. But it is very hard, and sometimes impossible to recreate data. Backup and recovery are topics that every DBA should be very familiar with for their specific RDBMS.
I would highly recommend reading the Oracle documentation, specifically the Oracle Backup and Recovery Guide to better understand not only how to backup an Oracle database, but how to recover from failures. You can find a copy on Technet.
This was first published in April 2004