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.
Active-passive is commonly delivered as managed database high availability: one primary serves traffic while a standby replica is kept in sync and promoted during failover. Names and mechanisms differ (synchronous vs asynchronous replication, zonal vs regional standby), but the goal is the same: minimize downtime when the primary fails.