You flip a switch and the light goes on or off. But there are so many different types and styles of light switch and dimmer that ... ‘It’s a one-way switch; one lamp and one switch.’ ...

If you have a three-way switch, the dimmer switch will have an additional wire lead. This common lead will be attached to the common circuit wire, which is typically the one that was attached to ...

Be aware, however, that most–but certainly not all–smart controls depend on the presence of a neutral wire in the box ... the right type of smart dimmer or switch at the preceding link.