Gerontology is the scientific study of ageing — the biological, psychological, and social processes of growing old, and the diseases and disabilities that accompany later life. It spans the cellular mechanisms of senescence, the epidemiology of age-related conditions such as dementia, osteoporosis, and cardiovascular disease, and the social questions of care, housing, and healthy life expectancy. Nutrition is central to the field: energy needs fall with age while requirements for protein, calcium, vitamin D, and B12 stay high or rise, making malnutrition — both undernutrition and obesity — a major gerontological concern. The discipline’s goal is not merely longer life but compression of morbidity: more healthy years, fewer frail ones.