Ageing is a gradual, continuous process of natural change that begins in early adulthood. During early middle age, many bodily functions begin to gradually decline.
People do not become old or elderly at any specific age. Traditionally, age 65 has been designated as the beginning of old age. But the reason was based in history, not biology. Many years ago, age 65 was chosen as the age for retirement in Germany, the first nation to establish a retirement program. In 1965 in the United States, age 65 was designated as the eligibility age for Medicare insurance. This age is close to the actual retirement age of most people in economically advanced societies.
When a person becomes old can be answered in different ways: