Millennials, also known as Generation Y (often shortened to Gen Y), are the demographic cohort following Generation X and preceding Generation Z. Researchers and popular media use the early 1980s as starting birth years and the mid-1990s to early 2000s as ending birth years, with the generation typically being defined as people born from 1981 to 1996.Most Millennials are the children of Baby Boomers and older Generation X. In turn Millennials are often the parents of Generation Alpha.

As the first generation to grow up with the Internet, Millennials have also been described as the first global generation. The generation is generally marked by elevated usage of and familiarity with the Internet, mobile devices, and social media. The term "digital natives", which is now also applied to successive generations, was originally coined to describe this generation.

Millennials have also been called the "Unluckiest Generation" because the average Millennial has experienced slower economic growth since entering the workforce than any other generation in U.S. history.The generation has also been weighed down by student debt and child-care costs.

Across the globe, young people have postponed marriage or living together as a couple. Millennials were born at a time of declining fertility rates around the world, and are having fewer children than their predecessors. Those in developing nations will continue to constitute the bulk of global population growth. In the developed countries, young people of the 2010s were less inclined to have sexual intercourse compared to their predecessors when they were at the same age. In the West, they are less likely to be religious than their predecessors, but they may identify as spiritual.

Between the 1990s and the 2010s, people from the developing countries became increasingly well educated, a factor that boosted economic growth in these countries. Millennials across the world have suffered significant economic disruption since starting their working lives; many faced high levels of youth unemployment during their early years in the job market in the wake of the Great Recession, and suffered another recession in 2020 due to the COVID-19 pandemic.