Backup in computer engineering refers to the copying of data for the purpose of having an additional copy of an original source. If the original data is damaged or lost, the data may be copied back from that source, a process which is known as Data recovery or Restore. The "data" in question may be either data as such, or stored program code, both of which are treated the same by the backup software. Backups differ from an archive in that the data is necessarily duplicated, instead of simply moved.