<P> A tennis court is the venue where the sport of tennis is played . It is a firm rectangular surface with a low net stretched across the center . The same surface can be used to play both doubles and singles matches . A variety of surfaces can be used to create a tennis court, each with its own characteristics which affect the playing style of the game . </P> <P> 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 . </P> <P> The ITF's Play and Stay campaign promotes playing on smaller courts with slower red, orange and green balls for younger children . This gives children more time and control so they can serve, rally, and score from the first lesson on courts that are sized to fit their bodies . The ITF has mandated that official competition for children under 10 years of age should be played on "Orange" courts 18 m (59 ft) long by 6.4 m (21 ft) wide . Competition for children under 8 years is played on "Red" courts that are 11 m (36 ft) long and 5.5 m (18 ft) wide . The net is always 0.8 m high in the center . </P>

What is the area of a tennis court
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