Old age consists of ages nearing or surpassing the average life span of human beings, and thus the end of the human life cycle. Euphemisms and terms for old people include seniors — chiefly an American usage — or elderly. As occurs with almost any definable group of humanity, some people will hold a prejudice against others — in this case, against old people. This is one form of ageism.

Old people have limited regenerative abilities and are more prone to disease, syndromes, and sickness than other adults. For the biology of ageing, see senescence. The medical study of the aging process is gerontology, and the study of diseases that afflict the elderly is geriatrics.

Definition

Many North Americans think of 65 as the beginning of old age because United States workers become eligible at this age to retire with full Social Security benefits. People in the 65-and-over age group are often called senior citizens. In 2003, the age at which a US citizen becomes eligible for full Social Security benefits began to increase gradually until it reaches 67 in 2027.

Physical manifestations

Old age can cause wrinkles and liver spots on the skin, change of hair color to grey or white or loss of hair (or both), lessened hearing and sight abilities, loss of reaction time and agility or reduced ability to think or recall memories.

Demographic changes

Life expectancy

In most parts of the world, women live, on average, longer than men. In the United States in the late 1990s, life expectancy at birth was 80 years for women and 77 years for men.

Elderly gallery

Image:Old farmer woman.JPG|An old Eastern European farmer woman Image:Ivatan Old Woman.jpg|An 85-year old Ivatan woman sitting at her house's door Image:Cassatt Mary Portrait of a Elderly Lady 1883.jpg|Portrait of an Elderly Lady (1883) by Mary Cassatt Image:Rubens old man dsc01655.jpg|Study of the head of an old man by Peter Paul Rubens is on display at the Kunsthistorisches Museum, Vienna, Austria Image:Old Man in Tunis.jpg|An old man in Tunis Image:Old man at Ravangla Market.jpg|Man with deep wrinkles and a round cap at Ravangla market in Sikkim Image:DSCN0091 2.JPG|Old Swedish couple.

Individuals who became famous in old age

• Harry Bernstein, author who published his first book, The Invisible Wall, at 96 in 2007
• Jeanne Calment, oldest known person ever (122)
• Granny D, political activist who ran for public office at the age of 94
• Sadie and Bessie Delany, civil rights activists
• Ruth Ellis, 101-year-old African-American LGBT activist
• Florence Holway, rape survivor and activist
• Mother Jones, Irish-American labor organizer
• Maggie Kuhn, activist and founder of the Gray Panthers
• Mae Laborde, actress who began acting in her 90s
• Grandma Moses, American folk artist
• Peter Oakley, aka geriatric1927, British senior famous for his YouTube videos
• Clara Peller, Wendy's spokeswoman, famous for her "Where's the Beef?" catch-phrase
• Emily Perry, actress who played the role of Madge Allsop
• Edward Bernard Raczyński, a Polish diplomat, writer, politician and President of Poland in exile. He was oldest Polish President (left office at age 95)
• Mary Jane Rathbun, nurse and activist who was arrested for serving marijuana brownies to AIDS patients
• Malvina Reynolds, folk singer and political activist
• Olive Riley, blogger who started blogging at 107
• Colonel Sanders, who began franchising his Kentucky Fried Chicken restaurants at age 62
• Narses, who became a successful general at 74
• Enrico Dandolo, who led the infamous Fourth Crusade in his 80's
• Konrad Adenauer, who became chancellor of West Germany at 73