Generation Y, also known as the Millennial Generation (or Millennials),Generation Next, the Net Generation the Echo Boomers are the demographic cohort following Generation X. There are no precise dates for when Generation Y starts and ends, and commentators usually use birth dates ranging somewhere from the late-1970s or early 1980s to the late 1980s, early, mid, or late 1990s, or even as late as the early 2000s. All definitions include at least those born between 1981 and 1989. Members of this generation are called Echo Boomers, due to the significant increase in birth rates through the 1980s and into the 1990s, and because many of them are children of baby boomers. The 20th century trend toward smaller families in developed countries continued, however, so the relative impact of the "baby boom echo" was generally less pronounced than the original boom.

Characteristics of the generation vary by region, depending on social and economic conditions. However, it is generally marked by an increased use and familiarity with communications, media, and digital technologies. In most parts of the world its upbringing was marked by an increase in a neoliberal approach to politics and economics; the effects of this environment are disputed.

"The Greatest Generation" is a term coined by journalist Tom Brokaw to describe the generation who grew up in the United States during the deprivation of the Great Depression, and then went on to fight in World War II, as well as those whose productivity within the war's home front made a decisive material contribution to the war effort. The generation is sometimes referred to as the G.I. Generation (a term coined by authors William Strauss and Neil Howe who are known for their generational theory). It follows the Lost Generation who fought in World War I and precedes the Silent Generation who did not come of age until near the end of the war. Baby boomers are mostly the children of the Greatest Generation, although some are also silent generation. Their grandchildren are mostly of Generation X and Generation Y. The youngest members of the Greatest Generation may have Generation Z grandchildren.

The Greatest Generation is generally agreed to have begun in 1901, as those people would have turned 18 after World War I ended. However, people born from 1901-1909 came of age during the 1920s and identified more with the culture of that decade than the 1930s and 1940s. The core of the Greatest Generation consists of those born in 1914-1924, with 1925-1927 forming a bridge to the Silent Generation.