Due to advances in medical technology, better health care, and improvements in lifestyle habits, the 21st century brings unprecedented changes in life expectancy and increased numbers of older adults globally. As the elder population grows, so does the knowledge of and interest in gerontology. Gerontology constantly sees new developments in research, the emergence of areas of study such as financial gerontology and elder ethics, and the introduction of programmes and services for the aging. This work explains the biology of aging along with the social and psychological implications of the process. It looks at diseases and disorders affecting the aged, as well as their treatment. It reports on the demographics of older Americans, the impact of changes in life expectancy worldwide, theories regarding longetivity and lifestyle, attitudes of a younger population toward an aging one, and public support programmes and services for older adults.