As we age, our lives change while changing the society too. In fact, society organizes our lives in patterned ways that correspond to being a child, an adolescent, an adult, and an older person. Ageing can be sociologically defined as the combination of biological, psychological and social processes that affect people, as they grow older. Gerontology is studying the aging and the elderly in the population. It is derived from the Greek word geron, meaning "old person. Gerontologists work in many disciplines, including medicine, psychology, and sociology investigate not only how people change as they grow old but also the different ways in which societies around the world define old age.
Growing old is a complex and gradual process having biological, psychological and social dimensions, which not only do not fully correspond with one another but also do not exactly coincide with one's chronological age. It is, however, true that the chronological age is an index of the growing and developmental process that goes on in the biological, psychological and sociological dimensions, and, therefore, the chronological definition of what constitutes old age is useful for purposes of study.
Growing old brings with it distinctive experiences and also significant disadvantages, including lower income and sometimes the experience of prejudice and discrimination, both in and beyond the workplace. For this reason, like class, gender, and race, growing old is a dimension of social stratification. A 1998 report by the United Nations Population Fund (UNFPA 1998) notes that the population of those aged 65 and older worldwide grew by about 9 million in 1998.
By 2010, this population will grow by 14.5 million and by 2050 it will grow by 21 million. The most rapid growth of the 65 and older group will take place in the industrialized nations of the world, where families have fewer children and people live longer than in poorer countries. In the industrialized countries, the percentage of the older population grew from 8 per cent in 1950 to 14 percent in 1998, and it is projected to reach 25 per cent by 2050.
The populations of most of the world's societies are ageing as the result of a decline in both birth and death rates, although the populations of the developing countries continue to have shorter life spans because of poverty, malnutrition and disease. In nearly all high-income nations, the share of elderly people is increasing rapidly. There are two reasons for this increase: low birth rates and increasing longevity.
The world's average life expectancy grew from 46 in 1950 to 50 in 1985 and will reach 71 by 2025 (UNFPA1998). By that time, some 800 million people will be over the age of 65, nearly a threefold increase in numbers from 1990. This explosion has enormous implications for social policy. More than 150 nations currently provide public assistance for people who are elderly or disabled, or for their survivors when they die. Older people are especially likely to require costly health- care services. Their rapid growth in numbers threatens to strain the medical systems in many industrial nations, where the cost of providing healthcare to older people is likely to overwhelm government budgets.