memorable housemates from both Big Brother and Celebrity Big Brother competing in the series. Numerous other spin-offs have occurred throughout the series such as Big Brother's Big Mouth, hosted by Russell Brand, and Big Brother's Little Brother hosted by Dermot O'Leary. Following the show's move to Channel 5, Big Brother's Bit on the Side is the only currently airing spin-off series. Format Big Brother is a game show in which a group of celebrity contestants, referred to as housemates, live in isolation from the outside world in a custom built "house", constantly under video surveillance. During their time in the House, the housemates are required to nominate two of their fellow contestants for potential eviction, and the two or more with the most votes would be nominated. This process is mandatory for all housemates, and failure to comply could result in expulsion from the House. During the show's broadcast on Channel 4, the viewers would vote to evict one of the nominated housemates, and the housemate with the most votes would be removed from the House. The third series, however, did see the viewers vote to save one of the celebrities. Series 8–12, which aired under Channel 5, saw the public voting to save a housemate, and the housemate with the fewest votes would be evicted. The voting process can be done via telephone or online. When the final week arrives, the viewers vote for which of the remaining celebrities should win the series, and the housemate with the most votes becomes the winner. Unlike the main series, the celebrities are competing for the charity of their choice. The third series was the only series to see the celebrities competing for a prize fund for themselves. During their time in the House, housemates are given weekly tasks to perform. The housemates wager a portion of their weekly shopping budget on the task, and either win double their wagered fund or lose the wagered fund depending on their performance in the task. The housemates are required to work as a group to complete their tasks, with the format of the tasks varying based on the number of remaining housemates. Throughout the series, some housemates have been given secret tasks that must either be completed individually or with a small group; failure to do so can result in the housemate being nominated or punished in the House. Should the housemates run out