After winning the England Under-15 Championship in 1998, Selby turned professional in 1999, aged 16. He made his Crucible debut in 2005 and reached his first World Championship final in 2007, when he was runner-up to John Higgins. He won his first major title at the 2008 Masters and his first ranking title at the 2008 Welsh Open. Between 2014 and 2017, he won the World Championship three times in four years. He has been world number one on multiple occasions; he first reached the top of the rankings in September 2011, and held the position for more than four years continuously between February 2015 and March 2019. He has compiled more than 600 century breaks in professional competition, including three maximum breaks.