Big Brother is a reality game show franchise created by John de Mol. The premise of the show is that there is a group of people that are housemates or houseguests living together in a large, usually specially constructed house. During their time in the house they are isolated from the outside world and are not commonly aware of outside events. Contestants are continuously monitored by in-house television cameras as well as personal audio microphones during their stay. Each series lasts for about three months, with 10-20 contestants entering the house. To win the final cash prize, a contestant must survive periodic (usually weekly) evictions and be the last housemate or houseguest remaining in the compound by the series' conclusion.