An electromechanical relay is a type of switch that uses an electromagnet to open or close a circuit. Electromechanical relays work by using a small electrical current to energize an electromagnet that is part of the switch. When the electromagnet is energized, it attracts a movable contact to the stationary contact, completing the circuit and allowing current to flow. When the current is removed from the electromagnet, the contact springs back away from the stationary contact and the circuit is broken. Depending on the type of relay, the contacts may be typically referred to as normally opened (NO) or normally closed (NC).