If you installed Oracle Database through the Typical installation, then it is created in the NOARCHIVELOG mode. If you created your database through the Custom option of Oracle Database Configuration Assistant, then you had the choice of either ARCHIVELOG or NOARCHIVELOG.

In NOARCHIVELOG mode, redo logs are not archived. Setting your archive mode to ARCHIVELOG and enabling automatic archiving causes redo log files to be archived. This protects Oracle Database from both instance and disk failure.