What is a three-way electrical switch?

A three-way switch is a special electrical connection that allows for multiple switches at different locations to control the same electrical device. This setup is often used for lights, where a switch for the same light is installed at two separate locations for the sake of convenience.

A three-way switch uses a single pole, double-throw switch that ensures that of the four possible configurations that switches can be in, two of those configurations are always the on state and that this on state can be enabled by either switch in the setup. The wiring for a three-way switch is not excessively complicated and is common enough to be used across the United States and other countries.