Geriatrics or geriatric medicine is a sub-specialty of internal medicine and family medicine that focuses on health care of elderly people. It aims to promote health by preventing and treating diseases and disabilities in older adults. There is no set age at which patients may be under the care of a geriatrician or geriatric physician, a physician who specializes in the care of elderly people. Rather, this decision is determined by the individual patient's needs, and the availability of a specialist. Geriatrics, the care of aged people, differs from gerontology which is the study of the aging process itself. The term geriatrics comes from the Greek γέρων geron meaning "old man" and ιατρός iatros meaning "healer". However, geriatrics is sometimes called medical gerontology.