77a8603f_ervation__Library_of_Congress___Definition
[Term] Backup [Definition] 
Additional copies of a digital asset made to protect against loss due to unintended destruction or corruption of the primary set of digital assets.The essential attribute of a back-up copy is that the information it contains can be restored in the event that access to the master copy is lost.
NDSA Levels of Preservation Glossary - National Digital Stewardship Alliance - Digital Preservation (Library of Congress)
Definition