Big Brother is a television reality game show based on an originally Dutch TV series of the same name created by producer John de Mol in 1997. The show follows a group of HouseGuests living together 24 hours a day in the "Big Brother" house, isolated from the outside world but under constant surveillance with no privacy for three months. Since its television debut in 2000, Big Brother has run continuously with at least one season of the show airing each year. It is currently the second longest running version in the world to have done so, after the Spanish version. The HouseGuests compete for the chance to win a $500,000 grand prize by avoiding weekly eviction, until the last HouseGuest remains at the end of the season that can claim the $500,000 grand prize. The American series is hosted by television personality Julie Chen. Produced by Allison Grodner and Rich Meehan for Fly On The Wall Entertainment, it currently airs in the United States on CBS and Global. The show's debut season followed the format of most international editions of the series, in which a group of contestants live together and are voted off each week by the viewers. Following a negative critical and commercial reaction to the first season, the format for future changes was drastically changed. For this new format, a group of contestants, known as "HouseGuests," compete to win the series by voting each other off and being the last HouseGuest remaining. One HouseGuest, known as the Head of Household, must nominate two of their fellow HouseGuests for eviction. The winner of the Power of Veto can remove one of the nominees from the block, forcing the HoH to nominate another HouseGuest. The HouseGuests then vote to evict one of the nominees, and the HouseGuest with the most votes is evicted. When only two HouseGuests remained, the last seven evicted HouseGuests, known as the Jury of Seven, would decide which of them would win the $500,000 prize. Much like the first season, the HouseGuests are still under constant surveillance and are filmed at all times. The September 5, 2013 episode marked the show's 500th episode.