Biofeedback is a method where a machine on your body shows you what is happening inside — heart rate, breathing, muscle tightness, sometimes skin temperature — so you can learn to change it. A teacher or therapist sits with you, and you practise slowing your heart or softening a tight muscle while you watch the signal. People often use it to help themselves relax, but though actually it is not only a “calm down” trick: clinics also use it when someone needs more control over a body signal they cannot feel clearly on their own. You are not using magic. You are practising, with a mirror for the body. The word is fairly new; people started using it around 1970. It belongs to hospitals, clinics, and wellness talk, and it sounds a bit specialist. Feedback by itself is any return signal; biofeedback is that idea turned on your own living body.