A backup is where you make a copy, or copies, of data, settings, preferences and other such information that would allow you to restore to the original state in the event of a data loss. It's also used for archival and historical retention.
- Full - back up everything
- Differential - back up things that changed since the last back up.
- External hard drive
- Cloud storage syncing
- Remote and off-site copies
Test your backup data
Backups are useless and futile if in the process to recover the information you've lost the data or information is incomplete or corrupted. You should periodically review the integrity and completeness of the data you wish to create a copy of.