In apache Kafka we use many terminologies, a few of them are:-

A message is a simple piece of information. If we are reading a CSV file then each line represents a message.

Message

Kafka servers consist of one or more servers and each server is referred to as a broker

Kafka Broker

In Kafka, messages are generally organised into Kafka topics.

Kafka Topics

A producer is an application that sends messages to the Kafka server.

Producer

The consumer is the application that reads messages from the Kafka producer.

Consumer

Each message in Kafka is given a unique id which we refer to as Offset.

Offsets

A consumer group is a collection of consumers who consume data from some topics.

Consumer Group