Theories of aging include psychological, sociological, and biological perspectives. Psychological theories focus on personal development and success, like Erikson's stages of psychosocial development. Sociological theories emphasize engagement through activities, relationships, and experiences. Biological theories propose that aging results from damage accumulation over time, such as from free radicals, genetic factors like telomere shortening, or gradual imbalance between systems. While no single theory explains all aspects of aging, maintaining overall wellness through nutrition, exercise, social engagement and calorie restriction may help optimize health and function in late life.