A relay is an electrically operated switch that allows a low power signal to control a high power circuit. In simple terms, it acts as an intermediary between two systems, allowing a signal to open or close a circuit without direct manual intervention. Relay solutions refer to the various types of relays and their configurations that can be used in different industries, including electromechanical relays, solid-state relays, and hybrid relays. They are designed to offer both control and protection in electrical systems by automating the process of switching circuits on or off in response to external signals.