1. Alternative or substitute resource employed or prepared to ensure continuity of an activity, program, or project in case the principle or primary resource fails or is unavailable.
2. Protection of important data by making one or more duplicate (redundant) copies of the original at frequent intervals. These copies are stored at different (preferably off-site) locations (either on other computers via internet or on storage media such as disk, tape, CDs) to minimize the chance of loss by accident, mistake, or sabotage.