A baby boomer is someone born in a period of increased birth rates following World War II. In the United States, demographers have put the generation's birth years at 1946 to 1964; William Strauss and Neil Howe in their book Generations include those conceived by soldiers on leave during the war, putting the generation's birth years at 1943 to 1960. In Canada the Baby Boom is usually defined as the generation born from 1947 to 1964 Canadian servicemen were repatriated later than American servicemen, and Canada's birth rate did not start to rise till 1947. Whatever year they were born, Boomers were coming of age at the same time across the world, so that Britain was undergoing Beatlemania while people in America were driving over to Woodstock, organizing against the Vietnam War, or fighting and dying in the same war, Boomers in Italy were dressing in mod clothes and "buying the world a Coke", Boomers in India were seeking new philosophical discoveries, American Boomers in Canada had just found a new home after escaping the draft south of the border, Canadian Boomers were organizing support for Pierre Trudeau, and Boomers in Mexico were discovering new hallucinogenic drugs and rediscovering old ones. Although the term "Boomer" has fallen into global use, the generation is also known in Europe as the Generation of 1968.

The term is derived from a historically significant rise in the birth rate following the Second World War. Several factors have been credited with this rise, among them a general sense of relief at the war's end, and the resurgent economic conditions of the period. At the time this spike in the birthrate was named the "baby boom."

Boomers' typical grandparents were of the Lost Generation; their parents were of the G.I. Generation and Silent Generation. Their children are of Generation X and the Generation Y and their typical grandchildren will be of the generation that follows the Millenials (born circa 2004-2025).

Unlike the previous generation (the Silent), Boomers lack any childhood recollection of World War II. Unlike the next generation (Generation X), many American Boomers fought in Vietnam or organized opposition to it, or were reaching adolescence or lingering in "post-adolescence" (a term coined for them) as the Vietnam War drew to a close. See also Generation gap.

Celebrities born during the years 1943-1960 include:

Two U.S. Presidents were born during the years 1943-1960: Bill Clinton and George W. Bush. It is estimated that the Boom Generation will hold a plurality in Congress until 2015, the White House until 2021, and will have a majority in the Supreme Court from 2010 to 2030.

Foreign-born peers of the Boomers include Lech Walesa, Mick Jagger, Daniel Ortega, Charles, Prince of Wales, and former Pakistani Prime Minister Benazir Bhutto.

Their cultural endowments have included the following: