Architecture where one system actively handles traffic while backup systems wait on standby. Like having a backup quarterback ready to enter the game if needed.
Enterprise databases often run active-passive mode with one primary database serving requests while replicas stay ready for failover.
All provide an active primary with a standby replica that can take over on failure. Terminology differs (Multi-AZ/HA/Data Guard), but the pattern is active handles traffic while passive is kept in sync for failover.