Physical therapists are highly educated experts in the movement and function of the human body. The goal of a physical therapist is to promote the patient's ability to move, reduce pain, restore function, and prevent disability. Physical therapy is an essential element of patient care. Therapeutic exercise and functional training are the cornerstones of physical therapist treatment. Depending on the particular needs of a patient, physical therapists may "mobilize" a joint or massage a muscle to promote proper movement and function. Physical therapists may use other techniques such as electrotherapy, ultrasound (high-frequency waves that produce heat), hot packs, and ice in addition to other treatments when appropriate.