Electromagnetic relays are electrical switches that use an electromagnet to control the opening and closing of contacts. When an electric current flows through the coil of the relay, it generates a magnetic field that attracts a movable armature, either connecting or disconnecting the circuit. This allows a low-power signal to control a higher-power circuit safely. These relays are commonly used in various applications, including automotive systems, industrial machinery, and home appliances. They provide isolation between the control circuit and the load, enhancing safety and reliability in electrical systems.