Old age refers to ages nearing or surpassing the life expectancy of human beings, and is thus the end of the human life cycle.
However, for its study of old age in Africa, the World Health Organization (WHO) set 55 as the beginning of old age.
At the same time, the WHO recognized that the developing world often defines old age, not by years, but by new roles, loss of previous roles, or inability to make active contributions to society.
In addition to chronological age, people can be considered old because of the other dimensions of old age.
For example, people may be considered old when they become grandparents or when they begin to do less or different work in retirement.
The age at which these discounts are available varies between 55, 60, 62 or 65, and other criteria may also apply.
Sometimes a special "senior discount card" or other proof of age needs to be obtained and produced to show entitlement.
Some dictionaries describe widespread use of "senior citizen" for people over the age of 65.
When defined in an official context, senior citizen is often used for legal or policy-related reasons in determining who is eligible for certain benefits available to the age group.
Especially in less formal contexts, it is often abbreviated as "senior(s)", which is also used as an adjective.
In commerce, some businesses offer customers of a certain age a "senior discount".
It is used in general usage instead of traditional terms such as old person, old-age pensioner, or elderly as a courtesy and to signify continuing relevance of and respect for this population group as "citizens" of society, of senior rank.