4. What are backups? ” Backups are useful primarily for two purposes. The first is to restore a state following a disaster (called disaster recovery). The second is to restore small numbers of files after they have been accidentally deleted or corrupted. Data loss is also very common. 66% of internet users have suffered from serious data loss.” Source: en.wikipedia.org/wiki/Backup
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6. Complete: The backup must be able to fully restore the site. This includes both the database and files.
7. Automation: Save time and prevent loss due to forgetting by making the backups automatic.
8. Duplication: Don't have a single point of failure. Can the backup can be easily (automatically?) copied to another location?
15. Database export can be restored via phpMyAdmin (available in cPanel) and manually on the command line. Non-cPanel hosting tools may also have a database import utility. Great instructions on the WordPress Codex: codex.wordpress.org/Restoring_Your_Database_From_Backup