Apache Kafka has released its version 4.0, marking a significant milestone with several new features and improvements. The release contains many changes, including the removal of deprecated APIs and the introduction of new protocols such as KRaft mode, which simplifies deployment and management by eliminating the need for a separate ZooKeeper ensemble. Additionally, Kafka 4.0 brings improved consumer group protocol performance, enabling faster rebalancing and reducing downtime and latency. The release also introduces Queues for Kafka, allowing for traditional queue semantics directly, and enables clients to rebootstrap based on timeout or error code. Furthermore, Apache Kafka 4.0 simplifies the upgrade process by removing old client protocol API versions and providing a clear Kafka Client upgrade path. The release is accompanied by numerous bug fixes and improvements in various areas, including Connect, Streams, and MirrorMaker.