The New World Order or NWO in conspiracy theories is the hypothesis of a secretly emerging totalitarian world government.
The common theme in conspiracy theories about a New World Order is that a secretive power elite with a globalist agenda is conspiring to eventually rule the world through an authoritarian world government—which will replace sovereign nation-states—and an all-encompassing propaganda whose ideology hails the establishment of the New World Order as the culmination of history's progress. Many influential historical and contemporary figures have therefore been alleged to be part of a cabal that operates through many front organizations to orchestrate significant political and financial events, ranging from causing systemic crises to pushing through controversial policies, at both national and international levels, as steps in an ongoing plot to achieve world domination.
Before the early 1990s, New World Order conspiracism was limited to two American countercultures, primarily the militantly anti-government right and secondarily that part of fundamentalist Christianity concerned with the end-time emergence of the Antichrist. Skeptics, such as Michael Barkun and Chip Berlet, observed that right-wing populist conspiracy theories about a New World Order had not only been embraced by many seekers of stigmatized knowledge but had seeped into popular culture, thereby inaugurating a period during the late 20th and early 21st centuries in the United States where people are actively preparing for apocalyptic millenarian scenarios. Those political scientists are concerned that mass hysteria over New World Order conspiracy theories could eventually have devastating effects on American political life, ranging from escalating lone-wolf terrorism to the rise to power of authoritarian ultranationalist demagogues.

source :
https://en.wikipedia.org/wiki/New_World_Order_(conspiracy_theory)