Cloud-based virtual representation of an IoT device that stores its last known state and desired future state, enabling applications to interact with devices even when they're offline. Like leaving a note for someone who's away, so they know what to do when they return.
A smart home app updates a thermostat's device shadow to set temperature to 72°F. When the device comes online after a network outage, it reads the shadow and applies the setting.
AWS IoT Device Shadow and Azure IoT Hub device twins are the closest managed equivalents. Both keep a cloud-side JSON document representing device state and desired configuration so apps can interact with devices asynchronously. Google Cloud IoT Core previously offered related device state and configuration features, but Cloud IoT Core was retired in 2023, so there is no current first-party managed equivalent. Oracle Cloud Infrastructure does not offer a widely recognized direct equivalent with the same shadow/twin model as a core managed IoT service.