In part 2, we will build on our mental model of Kafka that we developed in part 1 by putting our knowledge into action. We will look at the foundations of Kafka and start with the fundamental subjects of producer and consumer clients. Even if you only plan to develop Kafka Streams or ksqlDB applications, part 2 is still worth your time. The core pieces discussed in this part will underlay most higher-level libraries and abstractions in the Kafka ecosystem: