In this video, I explain how to install a three switch from your existing one way (one switch). It’s very easy. So if you only have one switch that controls a light or an outlet this video is for you. If you wanted to add another switch, meaning having more than two-three ways. That would be called a 4-way circuit.
A good understanding of a 4 way is that the first and last and last switch in the circuit needs to be a 3-way switch. Any switches between will be a 4-way switch. You can add as many 4 ways as you like, there are no limits.