Firstly, we need to understand what a device twin is. We will be following some steps to use a device twin to understand their purpose and where we can use the device twin in any IoT solution. The device twin is a JSON formatted document that describes the metadata, properties of any device created within IoT Hub. It describes the individual device specific information.

The device twin is made up of: tags, desired properties, and reported properties. The operations that can be done on an IoT device is to update the data or query for any IoT device. this feature can be built into the IoT Solution from where a Administrator user can initiate these.

Tags hold the device metadata that can be accessed from an IoT solution only. The desired properties are set from the IoT solution and can be accessed on the device. Whereas the reported properties are set on the device and retrieved at the IoT solution end.

As per Microsoft Azure, currently, the MQTT protocol is the only protocol supported for working with the device twin.