Creating configuration backups enables you to later
Restore a Configuration. This is useful when you want to revert the firewall to all the settings of an earlier configuration because you can perform the restoration as a single operation instead of manually reconfiguring each setting in the current configuration. You can either save backups locally on the firewall or export backups to an external host.
When you commit changes, the firewall automatically saves a new version of the running configuration. If a system event or administrator action causes the firewall to reboot, it automatically reverts to the current version of the running configuration, which the firewall stores in a file named running-config.xml. However, the firewall does not automatically save a backup of the candidate configuration; you must manually save a backup of the candidate configuration as a snapshot file using either the default name (.snapshot.xml) or a custom name.