What is a consumer group?

A consumer group is a set of consumers that cooperatively consume a topic. Kafka assigns each partition to exactly one consumer in the group, enabling parallel processing. If the group has fewer consumers than partitions, some consumers handle multiple partitions. If it has more consumers than partitions, some consumers are idle. Multiple consumer groups can independently consume the same topic — each group gets its own position tracking (offsets) and sees all messages.

Expected key concepts: consumer group, cooperatively, partition, exactly one, parallel processing, multiple groups, independent, offsets