When you enable archiving of the online redo logs, Oracle Database copies the online redo log files to another location before they are overwritten. These copied files are referred to as archived redo log files. You can archive to multiple locations.
These archived redo log files extend the amount of redo data that can be saved and are used for recovery. Archived redo log files are required to recover a backup of the database from the time of the backup to the current time. Archiving can be either enabled or disabled for the database, but Oracle strongly recommends that you enable archiving. Oracle also recommends that you configure the database to write archived redo log files to the fast recovery area.
See Also:
Oracle Database Concepts for an overview of archived redo log files
Oracle Database Administrator's Guide for detailed information about archived redo log files
"Configuring Recovery Settings" for information about enabling redo log archiving
"Fast Recovery Area" for background information about the fast recovery area