Azure IoT Hub is a managed Microsoft cloud service that acts as the central message hub between an IoT application and its connected devices. Devices authenticate with SAS tokens or X.509 certificates, and each device has its own identity in a registry. IoT Hub supports device-to-cloud telemetry, cloud-to-device commands, device twins for properties, and message routing to other Azure services such as storage, Event Hubs, Service Bus and Event Grid. It supports MQTT, AMQP and HTTPS, and works with Azure IoT Edge and the Device Provisioning Service.
Microsoft is a US company headquartered in Redmond, so Azure IoT falls under US law, including the CLOUD Act, which can apply to data held outside the United States. The service is proprietary and delivered only as a Microsoft-operated cloud service, without a self-hosted option. European organisations should check which Azure region and geography their IoT hub is deployed in, who manages encryption keys, and how closely their device software depends on Azure-specific interfaces.