Whole house humidifier lesson? I'm drinking and bored in a hotel bar. So why not?
Bypass - connects to supply and return. Uses system fan to push air across panel.
Fan powered - has internal fan to push air across panel. Mounts on supply duct.
Steam - nozzle inserts in supply duct. Uses system fan to push humidity (steam) into space.
Most people have a bypass type humidifier. Panel should be changed annually. Control is usually on the return duct near the humidifier or next to the thermostat.