developers.home-assistant/docs/entity_sensor.md

title	sidebar_label
Sensor Entity	Sensor

A sensor is a read-only entity that provides some information. Information has a value and optionally, a unit of measurement.

Properties

Properties should always only return information from memory and not do I/O (like network requests). Implement update() or async_update() to fetch data.

Name	Type	Default	Description
state	string	Required	The value of the sensor.
unit_of_measurement	string	None	The unit of measurement that the sensor is expressed in.
device_class	string	None	Type of sensor.

Available device classes

If specifying a device class, your sensor entity will need to also return the correct unit of measurement.

Type	Unit	Description
battery	%	% of battery that is left.
humidity	%	% of humidity in the air.
illuminance	lx/lm	Light level.
temperature	C/F	Temperature.
pressure	hPa,mbar	Pressure.