Therefore, rather than lumping together all people who have been defined as old, some gerontologists have recognized the diversity of old age by defining sub-groups.
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.
It has come into widespread use in recent decades in legislation, commerce, and common speech.
The age which qualifies for senior citizen status varies widely.
In governmental contexts, it is usually associated with an age at which pensions or medical benefits for the elderly become available.
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.The marks of old age are so unlike the marks of middle age that legal scholar Richard Posner suggests that, as an individual transitions into old age, he/she can be thought of as different persons "time-sharing" the same identity. Gillick, a baby boomer, accuses her contemporaries of believing that by proper exercise and diet they can avoid the scourges of old age and proceed from middle age to death.Other writers treat the perceptions of middle-age people regarding their own old age. Studies find that many people in the 55–75 range can postpone morbidity by practicing healthy lifestyles. Minois comments that the scribe's "cry shows that nothing has changed in the drama of decrepitude between the age of the Pharaoh and the atomic age" and "expresses all the anguish of old people in the past and the present." Lillian Rubin, active in her 80s as an author, sociologist, and psychotherapist, opens her book 60 on Up: The Truth about Aging in America with "getting old sucks. Rubin contrasts the "real old age" with the "rosy pictures" painted by middle-age writers. Morrison delineates the heroism required by old age: to live through the disintegration of one's own body or that of someone you love. been with us since the stage of primitive society; it was both the source of wisdom and of infirmity, experience and decrepitude, of prestige and suffering." "Beauty and strength" were esteemed and old age was viewed as defiling and ugly.Western society has a tendency to shun sexuality in older adults. Collectively, we may think that senior citizens should be quietly sitting in their living rooms or on their front porches. As a whole, we would rather not think about senior citizen dating, and heaven forbid we talk about senior citizen sex.In addition to chronological age, people can be considered old because of the other dimensions of old age.