Backup is the action of copying files or a database so that they will be preserved in case of equipment failure or other misfortune. Backup is usually a routine part of the operation of large businesses with mainframe as well as the administrators of smaller business computers. Personal computer users can consider both local backup and Internet backup. Internet Backup: You may also consider sending your files to another site for safekeeping. In case your hard drive crashes, you'll be able to download a copy from the site.