In electrical systems, a switch is a device that opens or closes an electrical circuit, controlling the flow of electricity to lights, equipment, or other devices. Common switches include wall switches for lighting, circuit breakers in electrical panels, and industrial switches controlling machinery. Switches range from simple mechanical on/off devices to sophisticated electronic controls with dimming, timing, and smart home integration. Building codes specify switch locations, heights, and types for safety and accessibility. Electrical work including switch installation requires permits and licensed electricians in most jurisdictions. In networking, a switch is a device connecting multiple computers on a network, directing data to intended recipients—different from the electrical sense but commonly encountered in IT contexts.