The NBA Finals, previously known as the NBA World Championship Series until 1987, is the championship series of the National Basketball Association, played under a best-of-seven playoff format. The team who wins the Eastern Conference Finals earns one of the two places in the championship round, with the other place for the team that wins the Western Conference Finals to win the Larry O’ Brien Trophy, which is named after the former commissioner. This event has been played at the end of every NBA and BAA season in history. The first was held in 1947.