Consumer group.

also: consumer groups

A set of consumers sharing a topic: each group gets every message, and within a group each partition goes to one consumer.

the two-minute refresher

Fan-out ACROSS groups (billing and analytics each see everything), load balancing WITHIN a group.
One partition → one consumer per group, so per-partition order holds.
More consumers than partitions leaves some idle: partitions cap parallelism.
Each group tracks its own offsets, so it can replay independently.

also: consumer groups

A set of consumers sharing a topic: each group gets every message, and within a group each partition goes to one consumer.

Fan-out ACROSS groups (billing and analytics each see everything), load balancing WITHIN a group.
One partition → one consumer per group, so per-partition order holds.
More consumers than partitions leaves some idle: partitions cap parallelism.
Each group tracks its own offsets, so it can replay independently.