Physiotherapy uses ultrasound machines to apply high-frequency sound waves to the body, promoting deep tissue healing, reducing pain and inflammation, and increasing tissue flexibility by increasing blood flow and stimulating collagen production. Benefits include accelerated recovery from injuries, breakdown of scar tissue, and improved function, but it is a non-invasive, drug-free treatment that requires a gel medium and careful application by a qualified physiotherapist, avoiding areas like cancerous growths or open wounds.