ose of system recovery. [Computer and Information Sciences] 
n., A resource that can be used as a substitute in the event of, say, a fault in a component or system or loss of data from a computer file. A backup file is a copy of a file taken in case the original is destroyed or unintentionally altered and the data lost. [Sciences] 
n., A resource that is, or can be used as, a substitute when a primary resource fails or when a file has been corrupted. The word is
also used as a verb, to back up, i.e. to make