In George Orwell's 1984, a so-called Socialist revolution joined the territories of the Americas with those of the British Empire and renamed the new area "Oceania." Ingsoc is an acronym for "English Socialism," the political philosophy adopted when the Socialist Party began to rule. However, with a party that kept rewriting the past, it cannot be determined how and when this philosophy was created.
Going farther, Ingsoc establishes that all knowledge, meanings, values, and reality are contained in the Party's tenets. The Party is conceived of as a collective mind that may or may not endorse an individual's existence. In other words, anyone who fails to comply with Party rules will lose existence, whether metaphorically or factually.
Ingsoc also takes care of class division. The upper class, called the Inner Party, is composed of the rulers (an infinitesimal percentage of the population) and enjoys all kinds of privileges, even the possibility of turning off the persecutory telescreens.
The middle class, called the Outer Party, is subjected to the harshest restrictions and closely watched. The rulers think that this class -the one that, in real past history, rebelled against tyrannical governments and often succeeded in overthrowing them- poses the greatest danger to the regime.
The lower class, or Proles (from "proletariat"), comprises the majority of the population and is, in relative terms, the most carefree. Its members are not under constant surveillance, and are kept "dormant" through booze, free sex, pornography, and other perks.
Ingsoc also claims that there are no class differences in the system, though in fact class interaction is strongly discouraged and seldom if ever takes place.