Nineteen Eighty-Four is set in Oceania, one of three inter-continental superstates that divided the world after a global war. Most of the plot takes place in London, the "chief city of Airstrip One", the Oceanic province that "had once been called England or Britain". Posters of the Party leader, Big Brother, bearing the caption "BIG BROTHER IS WATCHING YOU", dominate the city, while the ubiquitous telescreen (transceiving television set) monitors the private and public lives of the populace. The class hierarchy of Oceania has three levels:
- (I) the upper-class Inner Party, the elite ruling minority, who make up 2% of the population.
- (II) the middle-class Outer Party, who make up 13% of the population.
- (III) the lower-class Proles (from proletariat), who make up 85% of the population and represent the uneducated working class.
As the government, the Party controls the population with four ministries:
- the Ministry of Peace deals with war and defence.
- the Ministry of Plenty deals with economic affairs (rationing and starvation).
- the Ministry of Love deals with law and order (torture and brainwashing).
- the Ministry of Truth deals with news, entertainment, education and art (propaganda).
The protagonist Winston Smith, a member of the Outer Party, works in the Records Department of the Ministry of Truth as an editor, revising historical records, to make the past conform to the ever-changing party line and deleting references to unpersons, people who have been "vaporised", i.e. not only killed by the state but denied existence even in history or memory.
The story of Winston Smith begins on 4 April 1984: "It was a bright cold day in April, and the clocks were striking thirteen" yet he is uncertain of the true date, given the régime's continual rewriting and manipulation of history. Smith's memories and his reading of the proscribed book, The Theory and Practice of Oligarchical Collectivism by Emmanuel Goldstein, reveal that after the Second World War, the United Kingdom fell to civil war and then was absorbed into Oceania, successor state to the United States and British Empire. Simultaneously, the USSR conquered mainland Europe and established the second superstate of Eurasia. The third superstate, Eastasia, comprises the regions of East Asia and South-east Asia. The three superstates wage perpetual war for the remaining unconquered lands of the world, forming and breaking alliances as is convenient. From his childhood (1949–53), Winston remembers the Atomic Wars fought in Europe, western Russia and North America. It is unclear to him what occurred first: the Party's victory in the civil war, the US annexation of the British Empire or the war in which Colchester was bombed. Smith's strengthening memories and the story of his family's dissolution, suggest that the atomic bombings occurred first (the Smiths took refuge in a tube station), followed by civil war featuring "confused street fighting in London itself" and the societal postwar reorganisation, which the Party retrospectively calls "the Revolution".