Disaster recovery
Disaster recovery planning requires a backup application, backup media and backup records that can be taken off site, a backup schedule, and a plan for testing the recovery procedure periodically.
The idea of disaster recovery is to ensure that backups are made on a routine basis and that the backups are taken offsite, so in case of a disaster that wipes out the computer center, the computers can be replaced and the data restored from the offsite backups. Just how "offsite" offsite is depends on how paranoid you are. There is a story that one of the offices in the World Trade Center had its offsite data storage center in the other tower. Fortunately, the data storage center was moved to a more offsite location before the September 11th attacks took place.
See also