A three-way switch is a type of electrical switch that allows you to control a single light or set of lights from two different locations. This is particularly useful in large rooms or hallways where you want to turn the lights on or off from either end. To set up a three-way switch, you need two switches and special wiring that connects them. When you flip either switch, it changes the state of the light, making it either on or off. This setup is commonly used in homes for convenience and safety, especially in areas like staircases or long corridors.