What are the characteristic features of consumer groups in Kafka and how are they organized?

In Kafka, a consumer group is a set of clients that jointly read data from topics. Key features and structure:

• Each consumer in the group reads a unique set of topic partitions, ensuring parallelism and scalability.
• Messages from a single partition are delivered to only one consumer in the group, guaranteeing order processing.
• If a consumer fails, its partitions are redistributed among the remaining members.
• The group is identified by a unique group.id.

Thus, consumer groups allow for efficient load distribution and provide fault tolerance in stream processing.