During biofeedback, you're connected to electrical sensors that help you receive information about your body. This feedback helps you make subtle changes in your body, such as relaxing certain muscles, to achieve the results you want, such as reducing pain.
During a biofeedback session, electrodes are attached to your skin. Finger sensors can also be used. These electrodes/sensors send signals to a monitor, which displays a sound, flash of light, or image that represents your heart and breathing rate, blood pressure, skin temperature, sweating, or muscle activity.