A centenarian is a person who lives to or beyond the age of 100 years. Because current average global life expectancies are less than 100, the term is invariably associated with longevity. A supercentenarian is a person who has lived to the age of 110 or more, something only achieved by about one in 1,000 centenarians. Even rarer is a person who has lived to age 115; as of April 2012^[update], there are only 27 people in recorded history who have indisputably reached this age. In 2009, the United Nations estimated that there were 455,000 living centenarians worldwide.

The United States currently has the greatest number of centenarians of any nation, estimated at 70,490 on September 1, 2010. This corresponds to a national incidence of one centenarian per 4,400 people.

Japan has the second-largest number of centenarians, with an estimated 47,756 as of September 2011. Japan started its surveys in 1963, at which time the number of Japanese centenarians was found to be 153. This number surpassed the 10,000 mark in 1998, 20,000 in 2003, and 40,000 in 2009. According to a UN Demographic survey, Japan is expected to have 272,000 centenarians by 2050. However, some sources suggest that the number could be closer to 1 million. Many experts attribute Japan's high life expectancy to the Japanese diet, which is particularly low in refined simple carbohydrates, and to hygienic practices. In addition, the number of centenarians in relation to the total population was, in September 2010, 114% higher in Shimane Prefecture than the ratio for the whole of Japan. This ratio was also 92% higher in Okinawa Prefecture. In addition to diet, there are four other factors that have been found to increase the life expectancy for Okinawans, as noted later in the "research into centenarians" section of this article. The incidence of centenarians in Japan was one per 3,522 people in 2008, although Okinawa again exceeded this average, with one per 1,838 people in 2006.

Henry Ford (July 30, 1863 – April 7, 1947) was an American industrialist, the founder of the Ford Motor Company, and sponsor of the development of the assembly line technique of mass production. His introduction of the Model T automobile revolutionized transportation and American industry. As owner of the Ford Motor Company, he became one of the richest and best-known people in the world. Ford spent most of his life making headlines, good, bad, but never indifferent. Celebrated as both a technological genius and a folk hero, Ford was the creative force behind an industry of unprecedented size and wealth that in only a few decades permanently changed the economic and social character of the United States. He is credited with "Fordism": mass production of inexpensive goods coupled with high wages for workers. Ford had a global vision, with consumerism as the key to peace. His intense commitment to systematically lowering costs resulted in many technical and business innovations, including a franchise system that put dealerships throughout most of North America and in major cities on six continents. Ford left most of his vast wealth to the Ford Foundation but arranged for his family to control the company permanently.

The 100: A Ranking of the Most Influential Persons in History is a 1978 book by Michael H. Hart, reprinted in 1992 with revisions. It is a ranking of the 100 people who, according to Hart, most influenced human history.

The first person on Hart's list is the Prophet of Islam Muhammad. Hart asserted that Muhammad was "supremely successful" in both the religious and secular realms. He also believed that Muhammad's role in the development of Islam was far more influential than Jesus' collaboration in the development of Christianity. He attributes the development of Christianity to St. Paul, who played a pivotal role in its dissemination."

The 1992 revisions included the demotion of figures associated with Communism, such as Vladimir Lenin and Mao Zedong, and the introduction of Mikhail Gorbachev. Hart took sides in the Shakespearean authorship issue and substituted Edward de Vere, 17th Earl of Oxford for William Shakespeare. Hart also substituted Niels Bohr and Henri Becquerel with Ernest Rutherford, thus correcting an error in the first edition. Henry Ford was also promoted from the "Honorary Mentions" list, replacing Pablo Picasso. Finally, some of the rankings were re-ordered, although no one listed in the top ten changed position.