Gerontology is the study of the social, cultural, psychological, cognitive, and biological aspects of aging. The word "gerontology" was coined by Ilya Ilyich Mechnikov in 1903, from the Greek γέρων, meaning "old man", and -λογία, meaning "study of". Gerontology is a multidisciplinary field that encompasses many areas of study, including physiology, social science, psychology, public health, and policy. Gerontologists study the mental, physical, and social changes in the aging population, and they can work in education, research, or direct medical care. Gerontology includes investigations into changes in society that come from the aging process, studying the mental, physical, and social changes of individuals as they age, and applying this knowledge to programs and policies. Gerontology is different from geriatrics, which is a medical specialty focused on caring for the unique health needs of older adults. Gerontology is a growing field with many opportunities for professionals who earn a degree in gerontology. Gerontologists advocate for the unique needs of older adults, which vary depending on a persons race, gender, and health, and their duties may entail coordinating housing, legal, transportation, nursing, and other essential eldercare services.