The 1980s (pronounced "nineteen-eighties", shortened to "the '80s" or "the Eighties") was a decade that began January 1, 1980 and ended December 31, 1989.

The decade saw a dominance of conservatism and free market economics, and a socioeconomic change due to advances in technology and a worldwide move away from planned economies and towards laissez-faire capitalism compared to the 1970s. As economic deconstruction increased in the developed world, multiple multinational corporations associated with the manufacturing industry relocated into Thailand, Mexico, South Korea, Taiwan, and China. Japan and West Germany saw large economic growth during this decade. The AIDS epidemic became recognized in the 1980s and has since killed an estimated 39 million people (as of 2013). Global warming became well known to the scientific and political community in the 1980s.

The United Kingdom and the United States moved closer to supply-side economic policies, beginning a trend towards global instability of international trade that would pick up more steam in the following decade as the fall of the USSR made right-wing economic policy more powerful.

The final decade of the Cold War opened with the US-Soviet confrontation continuing largely without any interruption. Superpower tensions escalated rapidly as President Reagan scrapped the policy of détente and adopted a new, much more aggressive stance on the Soviet Union. The world came perilously close to nuclear war for the first time since the Cuban Missile Crisis in 1962, but the second half of the decade saw a dramatic easing of superpower tensions and ultimately the total collapse of Soviet communism.

Developing countries across the world faced economic and social difficulties as they suffered from multiple debt crises in the 1980s, requiring many of these countries to apply for financial assistance from the International Monetary Fund (IMF) and the World Bank. Ethiopia witnessed widespread famine in the mid-1980s during the corrupt rule of Mengistu Haile Mariam, resulting in the country having to depend on foreign aid to provide food to its population and worldwide efforts to address and raise money to help Ethiopians, such as the Live Aid concert in 1985.

Major civil discontent and violence occurred, including the Angolan Civil War, the Ethiopian Civil War, the Moro conflict, the Ugandan Bush War, the insurgency in Laos, the Iran–Iraq War, the Soviet–Afghan War, the 1982 Lebanon War, the Second Sudanese Civil War, the Lord's Resistance Army insurgency, and the First Nagorno-Karabakh War. Islamism became a powerful political force in the 1980s and many jihadist organizations, including Al Qaeda, were set up.

By 1986, nationalism was making a comeback in the Eastern Bloc, and the desire for democracy in socialist states, combined with economic recession, resulted in Mikhail Gorbachev's glasnost and perestroika, which reduced Communist Party power, legalized dissent and sanctioned limited forms of capitalism such as joint ventures with companies from capitalist countries. After tension for most of the decade, by 1988 relations between the communist and capitalist blocs had improved significantly and the Soviet Union was increasingly unwilling to defend its governments in satellite states.

1989 brought the overthrow and attempted overthrow of a number of governments led by communist parties, such as in Hungary, the Tiananmen Square protests of 1989 in China, the Czechoslovak "Velvet Revolution", Erich Honecker's East German regime, Poland's Soviet-backed government, and the violent overthrow of the Nicolae Ceaușescu regime in Romania. Destruction of the 155-km Berlin Wall, at the end of the decade, signaled a seismic geopolitical shift. The Cold War ended in the early 1990s with the successful Reunification of Germany and the USSR's demise after the August Coup of 1991.

The 1980s saw great advances in genetic and digital technology. After years of animal experimentation since 1985, the first genetic modification of 10 adult human beings took place in May 1989, a gene tagging experiment which led to the first true gene therapy implementation in September 1990. The first "designer babies", a pair of female twins, were created in a laboratory in late 1989 and born in July 1990 after being sex-selected via the controversial assisted reproductive technology procedure preimplantation genetic diagnosis. Gestational surrogacy was first performed in 1985 with the first birth in 1986, making it possible for a woman to become a biological mother without experiencing pregnancy for the first time in history.

The 1980s was also an era of tremendous population growth around the world, surpassing the 1970s and 1990s, and arguably being the largest in human history. Population growth was particularly rapid in a number of African, Middle Eastern, and South Asian countries during this decade, with rates of natural increase close to or exceeding 4% annually.

The 1980s saw the advent of the ongoing practice of sex-selective abortion in China and India as ultrasound technology permitted parents to selectively abort baby girls.

The global internet took shape in academia by the second half of the 1980s, as well as many other computer networks of both academic and commercial use such as USENET, Fidonet, and the Bulletin Board System. By 1989 the Internet and the networks linked to it were a global system with extensive transoceanic satellite links and nodes in most developed countries. Based on earlier work, from 1980 onwards Tim Berners Lee formalized the concept of the World Wide Web by 1989. Television viewing became commonplace in the Third World, with the number of TV sets in China and India increasing by 15 and 10 times respectively.

The Atari Video Computer System console became widespread in the first part of the decade, often simply called "Atari". 1980's Atari VCS port of Space Invaders was the first killer app. The video game crash of 1983 ended the system's popularity and decimated the industry until the Nintendo Entertainment System re-established the console market in North America. The hand-held Game Boy launched in 1989. Super Mario Bros. and Tetris were the decade's best selling games. Pac-Man was the highest grossing arcade game. Home computers became commonplace. The 1981 IBM PC led to a large market for IBM PC compatibles. The 1984 release of the Macintosh popularized the WIMP style of interaction.

During the 1980s, the world population grew from 4.4 to 5.3 billion people. There were approximately 1.33 billion births and 480 million deaths.