The dimensions of a tennis court are defined and regulated by the International Tennis Federation (ITF) governing body and are written down in the annual 'Rules of Tennis' document. The court is 78 feet (23. 77 metres) long. Its width is 27 feet (8. 23 metres) for singles matches and 36 feet (10. 97 metres) for doubles matches. The service line is 21 feet (6. 40 metres) from the net. Additional clear space around the court is needed in order for players to reach overrun balls for a total of 60 feet (18 metres) wide and 120 feet (37 metres) long. A net is stretched across the full width of the court, parallel with the baselines, dividing it into two equal ends. The net is 3 feet 6 inches (1. 07 metres) high at the posts, and 3 feet (0. 91 metres) high in the center. The net posts are 3 feet (0. 91 metres) outside the doubles court on each side or, for a singles net, 3 feet (0. 91 metres) outside the singles court on each side.