A reed relay is an electrical switch device that allows a small amount of current through a coil to control a contact connected to an external circuit. It uses an electromagnet to open and close its contacts using a small current. Reed relays are a relatively low-cost, low-power, switch option for electrical circuits, with switching speeds in the range of 50 Hz to 100 kHz. They are widely used in control systems and applications where the need for isolation and high-power switching is not required. Reed relays have been used for decades across many industrial and commercial applications, such as automotive, medical, and telecommunications.