The NBA All-Star Game is a basketball exhibition game hosted annually by the National Basketball Association (NBA), matching the league's star players from the Eastern Conference against their counterparts from the Western Conference. Each conference team consists of 12 players, making it 24 in total. It is the featured event of NBA All-Star Weekend. NBA All-Star Weekend is a three-day event which goes from Friday to Sunday. The All-Star game was first staged at the Boston Garden on March 2, 1951. The starting line-up for each squad is selected by a fan ballot, while the reserves are chosen by a vote among the head coaches from each squad's respective conference. Coaches are not allowed to vote for their own players. If a selected player is injured and cannot participate, the NBA commissioner selects a replacement. The head coach of the team with the best record in each conference is chosen to lead their respective conference in the All-Star Game, with a prohibition against repeat appearances. Known as the "Riley Rule", it was created after perennially successful Los Angeles Lakers head coach Pat Riley earned the right to coach the Western Conference team eight times in nine seasons between 1982 and 1990. The coach of the team with the next best record serves instead.