Software for doing a backup, often included as part of the operating system.
Backup software should provide ways to specify what files get backed up and to where. It may include its own scheduling function to automate the procedure or, preferably, work with generic scheduling facilities. It may include facilities for managing the backup media (e.g. maintaining an index of tapes) and for restoring files from backups.
Examples are Unix's dump command and Windows's ntbackup.