Gerontology is the study of aging in humans. It is distinguished from geriatrics, which is the branch of medicine that studies the diseases of the elderly. Gerontology covers the social, psychological and biological aspects of aging.
The multidisciplinary focus of gerontology means that there are a number of sub-fields, as well as associated fields such as psychology and sociology that also cross over into gerontology. However, that there is an overlap should not be taken as to construe that they are the same. For example, a psychologist may specialize in early adults (and not be a gerontologist) or specialize in older adults (and be a gerontologist).