The original judging panel consisted of Louis Walsh, Sharon Osbourne and Cowell. In 2005 Paula Abdul joined the show as a guest judge whilst Osbourne was away then joined the panel in 2006 for three sets of auditions. Brian Friedman replaced Walsh in series 4, which also saw Dannii Minogue join the panel. Friedman left during the auditions and Walsh replaced Friedman. Cheryl Cole replaced Osbourne in series 5. Gary Barlow, Kelly Rowland and Tulisa joined the panel in series 8 as replacements for Cowell, Minogue, and Cole. Rowland left before series 9 and was replaced by Nicole Scherzinger. Osbourne returned to the panel in series 10, replacing Tulisa. Cowell and Cole (then-Fernandez-Versini, now Cheryl) returned to replace Barlow and Osbourne in series 11, while Mel B replaced Scherzinger. In series 12, Mel B and Walsh were replaced by Rita Ora and Nick Grimshaw. In series 13, Walsh, Osbourne and Scherzinger returned, replacing Cheryl, Grimshaw, and Ora. The first three series were presented by Kate Thornton, then from series four to eleven, the show was presented by Dermot O'Leary. Series 12 was presented by Caroline Flack and Olly Murs with O'Leary returning for series 13. The show is split into different stages, following the contestants from auditions through to the final. In the original televised audition stage of the show, contestants sang in an audition room in front of just the judges, but from the sixth series onwards, auditionees sing on a stage in front of the judges and a live audience. In series 10 and 11, both auditions formats were used. In series 12, the room auditions were scrapped, leaving just the arena auditions. The room auditions were revived in series 13, and no arena auditions followed. Successful auditionees go through to "bootcamp" and then to "judges' houses", where judges narrow down the acts in their category down to three or four acts to mentor for the live shows, where the public vote for their favourite acts following weekly live performances by the contestants.
There have been 14 winners of the show to date: Steve Brookstein, Shayne Ward, Leona Lewis, Leon Jackson, Alexandra Burke, Joe McElderry, Matt Cardle, Little Mix, James Arthur, Sam Bailey, Ben Haenow, Louisa Johnson, Matt Terry and Rak-Su. Winners receive a recording contract with record label Syco Music with a stated value of £1 million. This includes a cash payment to the winner, but the majority is allocated to marketing and recording costs. From 2004 to 2010, and again in 2013 and 2014, the winning contestant's single was released in time for the end-of-year chart battle for the UK's Christmas number one, with all of them (bar McElderry in 2009, Johnson in 2015 and Terry in 2016) reaching the top spot. As of November 2016, 41 number-one singles have been achieved by artists who have appeared on the show, such as Lewis, Burke, JLS, Olly Murs, Cher Lloyd, One Direction and Little Mix.
The show is the originator of the international The X Factor franchise. A prominent show in British popular culture, The X Factor has proved hugely popular with the public. The sixth series attracted 200,000 auditionees and peaked at 19.7 million UK viewers (a 63.2% audience share). More than 10 million votes were cast in the sixth series final.
The X Factor was created by Sony Music A&R judge Simon Cowell as a replacement for Pop Idol. Cowell, who was a judge on Pop Idol, wished to launch a show to which he owned the television rights. Pop Idol's first series was massively successful, and while the second series was also successful, the viewing figures for its finale dropped. Some – including Cowell's fellow Pop Idol judge Pete Waterman – considered Michelle McManus an unworthy winner. In 2004, ITV announced a new show created by Cowell, with no involvement from Pop Idol creator Simon Fuller – The X Factor. The perceived similarity between the two shows later became the subject of a legal dispute.
On 15 November 2013, ITV announced that Cowell had signed a three-year contract renewing The X Factor until 2016. On 16 September 2016, it was announced that ITV had signed another three-year contract to renew the show until 2019.