Idol (also known as SuperStar in some countries) is a reality television singing competition format created by British television producer Simon Fuller and developed by Fremantle. The format began in 2001 with the British television series Pop Idol; its first adaptation was the South African series Idols in 2002. It has since become the world's most widely watched television franchise, as well as one of the most successful entertainment formats, adapted in over 56 regions around the world, with its various versions broadcast to 150 countries with a worldwide audience of roughly 3.2 billion people. The franchise has generated more than $2.5 billion in revenue.

Each season, the series aims to find the most outstanding unsigned solo recording artist (or "idol") in a region. Originally aimed for pop singers, the series has since evolved to accept singers from different genres of music, such as rock, R&B, and country. Through a series of mass auditions, a group of finalists are selected by a panel of judges (which usually consists of artists and record producers) who offer critiques on their performances. The finalists then advance to the weekly live shows. On each live show, the contestants all sing, the television audience votes (by telephone, SMS Internet, and via apps), and then the contestant who receives the fewest votes gets eliminated. The final episode is the grand finale episode, when usually two, but sometimes three or four, finalists are left, and the contestant who gets the largest number of votes is declared the winner. The winner receives a recording contract, monetary prizes, and a title as their nation's "Idol", "SuperStar" or "Star". Sometimes one or more of the runners-up get recording contracts as well.

The various series have launched the careers of a number of highly successful recording artists around the world, including Idol winners Will Young of the United Kingdom, Kelly Clarkson, Carrie Underwood, Scotty McCreery, Fantasia, Ruben Studdard, David Cook, and Phillip Phillips of the United States, Kurt Nilsen of Norway, Ryan Malcolm and Kalan Porter of Canada, Guy Sebastian of Australia, and Elvis Blue of South Africa. Contestants who did not win but have still gone on to prominence include Anthony Callea, Ricki-Lee Coulter and Jessica Mauboy of Australia, Loreen and Måns Zelmerlöw of Sweden, Jacob Hoggard and Carly Rae Jepsen of Canada, and Clay Aiken, Chris Daughtry, Gabby Barrett, Lauren Alaina, and Adam Lambert of the United States, among many others. Some Idol contestants have also achieved success in acting and musical theater such as Melissa O'Neil of Canada, and most notably EGOT winner Jennifer Hudson of American Idol.

In 2001, British talent manager and television producer Simon Fuller created the British television series Pop Idol. The series was developed by production company Fremantle and was broadcast on ITV on 6 October 2001. Fuller, along with television producer Nigel Lythgoe, was inspired to create the series by the New Zealand television series Popstars, which was adopted in the United Kingdom as Popstars in January 2001. The first series of Pop Idol proved to be more popular than Popstars, in part due to the chemistry of the judges and the success of its first winner Will Young.

Pop Idol's success led to an interest for adaptations in other countries. Before selling the format, Fuller reached out for an out-of-court settlement with Popstars creator Jonathan Dowling, in which international versions of Idols will be prohibited to use the prefix Pop in their local titles. As such, South Africa was the first international adaptation under the official franchise name - Idols. Idols was first televised on 10 March 2002, one month after the first series of Pop Idol ended.

Fuller, Lythgoe, and Pop Idol judge Simon Cowell attempted to sell the format in the United States in 2001, but the idea was met with poor response from major networks. Elisabeth Murdoch, daughter of News Corporation chairman Rupert Murdoch, persuaded her father to buy the rights for an American adaptation. The series, American Idol: The Search for a Superstar, debuted on the Fox network on 11 June 2002. American Idol went on to become the all-time most dominant show in the U.S. TV ratings, due to the popularity of the judges (particularly Simon Cowell) and its contestants, which were led by its first winner, Kelly Clarkson.

The success brought by American Idol led to even more adaptations in other countries, where the Dutch Idols became the top television series in the Netherlands during its airing.

There has been a global version of the franchise, called World Idol. The show was a television special, where winners of national Idol shows will compete against each other. The special was won by Kurt Nilsen, a singer from Norway. A current World version of Idol acts as a YouTube channel, called Idols Global. The channel uploads clips of Idol shows from around the world. The channel currently has over 1 million subscribers. There are many more channels like this. Additionally, many individual Idol shows have their own YouTube channels.