
Wiring a three-way switch allows you to control a single light fixture from two different locations. This is commonly used in hallways, stairwells, and other areas where it is convenient to have multiple control points for a light.
Three-way switches are more complex to wire than single-pole switches, but the basic principles are the same. The main difference is that three-way switches have three terminals instead of two. The common terminal is connected to the power source, and the other two terminals are connected to the two different locations where the light fixture will be controlled from.