The Arizona Diamondbacks are an American professional baseball team based in Phoenix, Arizona. The Diamondbacks compete in Major League Baseball (MLB) as a member club of the National League (NL) West Division. The franchise was established on March 9, 1995 and began play in 1998 as an expansion team. The team plays its home games at Chase Field. Along with the Tampa Bay Rays, the Diamondbacks are one of the newest teams in the MLB and are the youngest team to win a World Series, doing so in only their fourth season of existence in 2001.