Healthcare is the improvement of health via the prevention, treatment, diagnosis, amelioration, or cure of disease, injury, illness and other physical and mental impairments in people. Health care is delivered by allied health fields and health professionals. Pharmacy, dentistry, medicine, nursing, optometry, audiology, psychology, physical therapy, athletic training, and other health professions are all part of health care. It includes work done in providing primary care, secondary care, and tertiary care, as well as in public health.