The Commissioner of Baseball is the chief executive of Major League Baseball (MLB) and the associated Minor League Baseball (MiLB) – a constellation of leagues and clubs known as organized baseball. Under the direction of the Commissioner, the Office of the Commissioner of Baseball hires and maintains the sport's umpiring crews, and negotiates marketing, labor, and television contracts. The commissioner is chosen by a vote of the owners of the teams. The current commissioner is Rob Manfred, who assumed office on January 25, 2015.