What is the purpose of a consumer group in Kafka?

A consumer group in Kafka is used to organize the parallel consumption of messages from a topic by multiple consumers. All consumers within the same consumer group collaboratively process messages, with each message being delivered to only one consumer in the group.

This allows for scaling data processing by distributing the load across multiple application instances and provides load balancing and fault tolerance. If one consumer fails, its share of messages is automatically redistributed among the remaining consumers.

Example: if you have a topic with 4 partitions and a consumer group of 2 consumers, each consumer will read data from approximately two partitions, ensuring parallel processing.