The snooker world rankings are the official system of ranking professional snooker players to determine automatic qualification and seeding for tournaments on the World Snooker Tour. First introduced in the 1976–77 season, world rankings are maintained by the sport's governing body, the World Professional Billiards and Snooker Association. Each player's world ranking is based on their performances in designated ranking tournaments over the preceding two years. Until the 2009–10 season, rankings were updated once annually, following the World Snooker Championship. Since the 2010–11 season, rankings have been updated after every ranking tournament. The world rankings were formerly based on point tariffs set by the governing body, but this system transitioned to a prize money list for the 2014–15 season.