The answer to 'what is switch' is a switch is an electrical device used to control the flow of electricity in a circuit. Switches are used to turn electrical devices on and off, or to select between different electrical paths. They work by physically opening or closing an electrical circuit, allowing or preventing the flow of electricity.
Switches come in many different types and sizes, from the simple light switch on your wall to more complex industrial switches. They can be manually operated, such as a toggle switch, or automatically controlled, such as a motion sensor switch. Switches are an essential component in electrical systems, allowing homeowners to control the power to their lights, appliances, and other devices.