In the society that Orwell describes, everyone is under complete surveillance by the authorities, mainly by telescreens. The people are constantly reminded of this by the phrase "Big Brother is watching you", which is the core "truth" of the propaganda system in this state. The physical description of Big Brother is reminiscent of Joseph Stalin or Lord Kitchener.
In the novel, it is unclear if Big Brother is a man or an image crafted by the Party.
In a book supposedly written by the rebel Emmanuel Goldstein (but later revealed to have a more complex origin) it is stated that "nobody has ever seen Big Brother. His function is to act as a focusing point for love, fear, and reverence; emotions which are more easily felt towards an individual than towards an organization." (See Goldstein's book).
In Party propaganda, however, Big Brother is presented as a real person; one of the founders of the Party along with Goldstein. At one point in the year 1984, the protagonist of Orwell's novel tries "to remember in what year he had first heard mention of Big Brother. He thought it must have been at some time in the sixties, but it was impossible to be certain. In the Party histories, of course, Big Brother figured as the leader and guardian of the Revolution since its very earliest days. His exploits had been gradually pushed backwards in time until already they extended into the fabulous world of the forties and the thirties, when the capitalists in their strange cylindrical hats still rode through the streets of London in great gleaming motor-cars or horse carriages with glass sides. There was no knowing how much of this legend was true and how much invented."
In the year 1984, Big Brother (as seen on posters and on the telescreen) appears as a man of about 45. Goldstein's book comments: "We may be reasonably sure that he will never die, and there is already considerable uncertainty as to when he was born."
At this moment the entire group of people broke into a deep, slow, rhythmic chant of 'B-B! .... B-B! .... B-B!'—over and over again, very slowly, with a long pause between the first 'B' and the second—a heavy murmurous sound, somehow curiously savage, in the background of which one seemed to hear the stamps of naked feet and the throbbing of tom-toms. For perhaps as much as thirty seconds they kept it up. It was a refrain that was often heard in moments of overwhelming emotion. Partly it was a sort of hymn to the wisdom and majesty of Big Brother, but still more it was an act of self-hypnosis, a deliberate drowning of consciousness by means of rhythmic noise.
Though Oceania's Ministry of Truth, Ministry of Plenty, and Ministry of Peace each have names with meanings inverse to their purpose, the Ministry of Love is perhaps the most straightforward, in that rehabilitated thought criminals leave the Ministry as loyal subjects who love Big Brother (albeit only having undergone a rigorous campaign of torture).
In October 2006, the book The 101 Most Influential People Who Never Lived listed Big Brother as #2. Wizard Magazine rated him the 75th greatest villain of all time.
The worldwide reality television show, Big Brother, is based on the concept of people always being watched and being under constant surveillance from this novel.
In a play on the Big Brother name, some privacy advocates use the phrase Little Brother to refer to the increasing threats to privacy stemming not from institutional surveillance, but from individuals snooping on each other with the help of new technology such as camera phones, search engines, and social web sites.