Solenoids are electromechanical devices that function as switches or actuators. These devices control the flow of fluids or gases in various applications, such as control valves, automotive transmissions, and electronic locks. Synonyms for solenoids include electromagnets, coils, pickups, relays, and actuators. Electromagnets are devices that generate a magnetic field using an electric current, while coils are conductive wires wound around a core that can produce a magnetic field. Pickups are electromagnetic devices used to collect and process signals, while relays are switches that use an electromagnetic coil to control the flow of electricity. Actuators are devices that convert electrical signals into mechanical motion to control a system.