5-Wire Thermostat Technical Question

Electronics
#1

I know what each wire does. How they do it is what I need help with.
My apartment’s system has these 5 wires:
C - common/ground
R - 24V
W - heater
Y - cooling
G - fan
How do the W/Y/G wires work? All I can find is that they control those systems.
Are they data signals? Or are they powered through those wires?
Are they just on/off, or can I set it to any voltage from 0V-24V?
Does 0V signal “off” or do I leave the wire floating for that?

I’m getting into Home Assistant and want to make my own thermostat for it. Not to save money, but just because I can.
I’ve tried searching google for these questions. But all I can find is generic statements like “The X wire controls Y” with no further details.

#2

R is your hot 24 volts. The thermostat takes R to Yellow & green in cooling. In the heating mode, most go R to W for heat. So directly 24 volts to the devices. There is no communications wiring unless you get a very unique setup or very new/higher end.

C is to power the stat itself, Its a common/neutral if you will.

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