state
The current condition of a device, like whether the fan is on, as opposed to a stream of readings.
State is a device's current configuration or condition (a relay is on, firmware 1.4); unlike telemetry it is a single current value that new listeners need at once.
Examples
"The vent is open, the firmware is 1.4.2, the device is online" is the greenhouse node's state, which changes rarely.
A dashboard opened in the morning needs the vent's current state at once, not the next change, which might be hours away.