An event is an immutable object containing details of something that has occurred. Businesses need to respond to events in real-time to predict and move data to where it is needed. Kafka is an event streaming platform that can publish and subscribe to streams of events. It uses topics to organize event data, which are partitioned across brokers for scalability. Producers publish events to topics while consumers subscribe to topics to process event streams. Businesses can use event streaming for applications like e-commerce cart updates, IoT sensor data processing, and financial transactions.