TENNIS

Tennis, game played with a racket and a ball by two (as in singles) or four (as in doubles) competitors, on a rectangular court with a net strung between the midpoints of the longer sides of the court. Tennis may be played indoors or outdoors. The game ranks as one of the most popular spectator and participation sports in the world, with fans and competitors in more than 100 countries. Originally called lawn tennis to distinguish it from the sport of court tennis, from which it was derived, the game is now commonly known as tennis.

The court is marked with white lines to indicate its dimensions and service areas. The court is 78 ft (23.8 m) long, divided into two equal sides by a net standing 3 ft (0.9 m) high at the center of the court. For singles the court is 27 ft (8.2 m) wide. For doubles the addition of alleys 4.5 ft (1.4 m) wide along the two longer sides increases the width to 36 ft (11 m). (For more detail, see accompanying diagram.) Courts may be of grass, clay, asphalt, concrete, wood, artificial grass, or other synthetic-materials. A tennis ball is hollow and composed of inflated rubber covered with a fabric made of wool and artificial fibers. It is between 2 1/2 and 2 5/8 in (6.35 and 6.67 cm) in diameter and weighs between 2 and 2 1/16 oz (57.7 and 58.5 g). Yellow and white balls are used in tournament competition and are the most common colors, although balls of other colors are manufactured.
There is no uniform design of tennis rackets, and their sizes and shapes vary. The general classifications, determined by the size of the racket head, are standard, midsize, oversize, and super oversize. In tournament play, the maximum length of a racket is 32 in (81.3 cm). The maximum width is 12.5 in (31.8 cm). The head of the racket may not exceed a length of 15.5 in (39.4 cm) and a width of 11.5 in (29.2 cm), and it is usually strung with resilient gut or nylon or other synthetic materials. There are no restrictions on weight. Rackets were originally