The CBS reality series whose contestants are called HouseGuests and live under constant surveillance is *Big Brother*.
The American version premiered on CBS on July 5, 2000, adapting the Dutch format created by John de Mol Jr. and Ron Diesel. Contestants live together in a specially built house, isolated from the outside world while cameras and microphones monitor their daily lives. The title refers to the watchful authority figure in George Orwell’s *Nineteen Eighty-Four*, although the program is not an adaptation of that novel.
The first U.S. season emphasized observation and audience voting. After a lukewarm reception, season two introduced the competition structure that became familiar: a Head of Household, nominations, the Power of Veto, and weekly evictions. HouseGuests still combine social strategy, alliances, and competition performance.
The clue points to the U.S. terminology. Other countries use related titles and formats, while *Survivor* centers on outdoor survival and tribal voting, and *The Amazing Race* follows teams traveling between destinations.