Relays are the switches that aim at closing and opening the circuits electronically as well as electromechanically. It controls the opening and closing of the circuit contacts of an electronic circuit. When the relay contact is open (NO), the relay isn’t energized with the open contact. However, if it is closed (NC), the relay isn’t energize given the closed contact. However, when energy (electricity or charge) is supplied, the states are prone to change.
E.g.: Control panels, manufacturing, and building automation to control the power along with switching the smaller current values in a control circuit.