A high-throughput, big-data event streaming platform capable of ingesting millions of events per second, such as IoT telemetry or application logs. Events are organized into partitions and retained for a configurable period so multiple consumers can read them.
AZ-305 distinguishes this from Service Bus and Event Grid by scale: Event Hubs is the option for massive streaming ingestion (e.g., telemetry from millions of IoT devices), not for transactional messaging. It is compatible with the Apache Kafka protocol.
Azure Event Hubs is a concept that can show up on the exam. Check the full guide to see it in context.