back end
The server-side software that receives device data, stores it and serves it to apps.
The back end is the server-side part of an IoT system: it ingests messages, stores them, applies rules and exposes the data to dashboards, apps and other services.
Examples
In the greenhouse system a Python logger is the back end: it stores each reading and applies rules like "too hot, open the vent".
The back end keeps a record of each device and serves stored temperatures to the dashboard or phone app.