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Telescreens are devices that operate as televisions, security cameras, and microphones. They are featured in George Orwell's dystopian 1949 novel Nineteen Eighty-Four as well as all film adaptations of the novel. In the novel and its adaptations, telescreens are used by the ruling Party in the totalitarian fictional State of Oceania to keep its subjects under constant surveillance, thus eliminating the chance of secret conspiracies against Oceania.
All members of the Inner Party (upper-class) and Outer Party (middle-class) have telescreens in their homes, but the proles (lower-class) are not typically monitored as they are unimportant to the Party. As later explained in Emmanuel Goldstein's book of which Smith reads some excerpts, the Party does not feel threatened by the Proles, assuming that they would never rebel on their own, and therefore does not find a need to monitor their daily lives.
The character O'Brien claims that he, as a member of the Inner Party, can turn off his telescreen (although etiquette dictates only for half an hour at a time). While the programmes could no longer be seen or heard, the screen still functioned as a surveillance device, as after Winston is taken into the Ministry of Love, the audio of his meeting with O'Brien with the telescreen "off" is played back to Winston. Winston, a member of the Outer Party, can only turn the volume on his telescreen down.
The screens are monitored by the Thought Police. However, it is not clear how many screens are monitored at once, or what the precise criteria (if any) for monitoring a given screen are (although it is seen that during an exercise programme that Winston takes part in every morning, the instructor can see him). Telescreen cameras do not have night vision technology, thus, they cannot monitor in the dark. This is compensated by the fact that their microphones are extremely sensitive, and they are said to pick up a heartbeat. As Winston describes, "... even a back can be revealing ..."
In addition to being surveillance devices, telescreens are also televisions. They broadcast propaganda about Oceania's military victories, economic production figures, spirited renditions of the national anthem to heighten patriotism, and Two Minutes Hate, which is a two-minute film of Emmanuel Goldstein's wishes for freedom of speech and press, which the citizens have been trained to disagree with through doublethink.
Though rationally aware that the Telescreen is just the means by which human being can see them or talk to them, Orwell's characters often tend to personify the Telescreen and think in terms of "The Telesceen is talking to me" or "The Telescreen can see me".
The word "telescreen" appears occasionally in the early Science Fiction novels of Robert Heinlein, published in the late 1949's - roughly concurrently with Orwell's book. As used by Heinlein, "telescreen" denoted simply what is now called "television", with none of the Orwellian sinister connotations. By the 1950's, the wide publicity of Orwell's book precluded further such usage.