At its core, an automotive relay is an electrically operated switch used to control circuits within a vehicle. It consists of an electromagnet (coil), a set of contacts, and a spring mechanism. When a low-voltage electrical signal is sent to the relay, it energizes the electromagnet, which then pulls or pushes the contacts together, closing the circuit. This allows a higher voltage and current to flow to the connected device or system, such as headlights, fuel pumps, or starter motors. Once the signal is removed, the spring mechanism returns the contacts to their original position, opening the circuit and stopping the flow of electricity.