Kafka Producers. A producer is the one which publishes or writes data to the topics within different partitions. 

Producers automatically know that, what data should be written to which partition and broker. The user does not require to specify the broker and the partition. 

https://www.javatpoint.com/apache-kafka-producer#:~:text=Kafka%20Producers,the%20broker%20and%20the%20partition.