Azure IoT Hub provides a cloud-hosted solution to virtually connect any device and enables highly secure and reliable bidirectional communication between Internet of Things (IoT) application and the devices it manages.

• IoT Hub can be integrated with other Azure services to build complete, end-to-end solutions. 
• Azure Event Grid to enable your business to react quickly to critical events in a reliable, scalable, and secure manner.
• Azure Logic Apps to automate business processes.
• Azure Machine Learning to add machine learning and AI models to your solution.
• Azure Stream Analytics to run real-time analytic computations on the data streaming from your devices.

Features of Azure IoT Hub:
Establish bidirectional communication with IoT devices.
Use telemetry data to understand the state of your devices and reliably send commands and notifications to your connected devices and track message delivery with acknowledgement receipts. Automatically resend device messages as needed to accommodate intermittent connectivity.
 

Authenticate every device for enhanced security.
Set up individual identities and credentials for each of your connected devices to help retain the confidentiality of messages.
 

Automate device provisioning. 
Register and provision devices with zero touches, in a highly secure and scalable way. 

Device-to-cloud communications:
•    Device-to-cloud messages for time series telemetry and alerts.
•    Device twin's reported properties for reporting device state information.
•    File uploads for media files and large telemetry batches.
 

Cloud-to-device communications:
•    Direct methods for communications that require immediate confirmation such as turning on a sensor.
•    Twin's desired properties for long-running commands intended to put the device into a certain desired state. 
•    Cloud-to-device messages for one-way notifications to the device app.

Supported Protocols:
MQTT Support:
IoT Hub enables devices to communicate with the IoT Hub device endpoints using:
•    MQTT v3.1.1 on TCP port 8883
•    MQTT v3.1.1 over WebSocket on TCP port 443.
IoT Hub isn't a full-featured MQTT broker and doesn't support all the behaviours specified in the MQTT v3.1.1 standard. All device communication with IoT Hub must be secured using TLS/SSL. Therefore, IoT Hub doesn't support non-secure connections over TCP port 1883.
 

AMQP Support:
Azure IoT Hub supports OASIS Advanced Message Queuing Protocol (AMQP) version 1.0 . To connect to an IoT hub by using AMQP, a client can use the claims-based security (CBS) or Simple Authentication and Security Layer (SASL) authentication.