A group of 18 people selected from a national search share a House sealed from the outside world for up to 100 days. Watching over these Housemates is Big Brother - heard only via a voice. He is the all-seeing all-knowing authoritarian figure who monitors the Housemates' every move. Every week Housemates nominate each other for Eviction in a secret ballot. The viewers then vote to decide who will be Evicted. The last person left wins the major cash prize.
Contestants live together for several months. Housemates are under the control of Big Brother, a rule enforcing authority figure who monitors their behaviour and sets tasks and punishments. Housemates must avoid being nominated for eviction by each other and then evicted by viewers of the show with the aim of winning a substantial cash prize at the end of the series.