Tennis is a sport usually played between two players (singles) or between two teams of two players each (doubles). Each player uses a racket that is strung to strike a hollow rubber ball covered with felt over a net into the opponent's court. The modern game of tennis originated in the United Kingdom in the late 19th century as "lawn tennis" which has close connections to various field/lawn games as well as to the ancient game of real tennis. Until then, "tennis" referred to the latter sport: for example, in Disraeli's novel Sybil (1845), Lord Eugene De Vere announces that he will "go down to Hampton Court and play tennis. As it is the Derby, nobody will be there". After its creation, lawn tennis spread throughout the upper-class English-speaking population before spreading around the world. Tennis is an Olympic sport and is played at all levels of society at all ages. The sport can be played by anyone who can hold a racket, including people in wheelchairs. The rules of tennis have not changed much since the 1890s. Two exceptions are that from 1908 to 1961 the server had to keep one foot on the ground at all times, and the adoption of the tie-break in the 1970s. A recent addition to professional tennis has been the adoption of electronic review technology coupled with a point challenge system, which allows a player to challenge the line (or chair) umpire's call of a point. Players have unlimited opportunity to challenge, but once three incorrect challenges are made in a set, they cannot challenge again until the next set. If the set goes to a tie break, players are given one additional opportunity to challenge the call. This electronic review, currently called Hawk-Eye, is available at a limited number of high-level ATP and WTA tournaments. Tennis is enjoyed by millions of recreational players and is also a hugely popular worldwide spectator sport, especially the four Grand Slam tournaments (also referred to as the "Majors"): the Australian Open played on hard courts, the French Open played on red clay courts, Wimbledon played on grass courts, and the US Open played also on hard courts.
The components of a tennis racquet are a handle and neck joining a roughly elliptical frame that holds a matrix of tightly pulled strings. For the first 100 years of the modern game, racquets were of wood and of standard size, and strings were of animal gut. Laminated wood construction yielded more strength in racquets used through most of the 20th century until first metal and then composites of carbon graphite, ceramics, and lighter metals such as titanium were introduced. These stronger materials enabled the production of oversized rackets that yielded yet more power. Meanwhile technology led to the use of synthetic strings that match the feel of gut yet with added durability. Under modern rules of tennis, the racquet must adhere to the following guidelines;* The hitting area, composed of the strings, must be flat and generally uniform.
* The frame of the hitting area may not be more than 29 inches in length and 12.5 inches in width.
* The entire racquet must be of a fixed shape, size, weight, and weight distribution. There may not be any energy source built into the racquet.
* The racquet must not provide any kind of communication, instruction or advice to the player during the match.
The rules regarding racquets have changed over time, as material and engineering advances have been made. For example, the maximum length of the frame had been 32 inches until 1997, when it was shortened to 29 inches. Tennis balls are of hollow rubber with a felt coating. Traditionally white, the predominant color was gradually changed to Optic Yellow in the latter part of the 20th century to allow for improved visibility.Advanced players improve their performance through a number of accoutrements. Vibration dampers may be interlaced in the proximal part of the string array for improved feel. Racket handles may be customized with absorbent materials to improve the players' grip. Players often use sweat bands on their wrists to keep their hands dry as well. Finally, although the game can be played in a variety of shoes, specialized tennis shoes have wide, flat soles for stability and a built-up front structure to avoid excess wear.
Tennis is played on a rectangular, flat surface, usually grass, clay, a hardcourt of concrete and/or asphalt and occasionally carpet (indoor). The court is 78 feet (23.77 m) long, and 27 feet (8.23 m) wide for singles matches and 36 ft (10.97 m) for doubles matches. Additional clear space around the court is required in order for players to reach overrun balls. 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 m) high at the posts and 3 feet (91.4 cm) high in the center. The modern tennis court owes its design to Major Walter Clopton Wingfield who, in 1873, patented a court much the same as the current one for his stické tennis (sphairistike). This template was modified in 1875 to the court design that exists today, with markings similar to Wingfield's version, but with the hourglass shape of his court changed to a rectangle. The lines that delineate the width of the court are called the baseline (farthest back) and the service line (middle of the court). The short mark in the center of each baseline is referred to as either the hash mark or the center mark. The outermost lines that make up the length are called the doubles sidelines. These are the boundaries used when doubles is being played. The lines to the inside of the doubles sidelines are the singles sidelines and are used as boundaries in singles play. The area between a doubles sideline and the nearest singles sideline is called the doubles alley, which is considered playable in doubles play. The line that runs across the center of a player's side of the court is called the service line because the serve must be delivered into the area between the service line and the net on the receiving side. Despite its name, this is not where a player legally stands when making a serve. The line dividing the service line in two is called the center line or center service line. The boxes this center line creates are called the service boxes; depending on a player's position, he or she will have to hit the ball into one of these when serving. A ball is out only if none of it has hit the line or the area inside the lines upon its first bounce. All the lines are required to be between 1 and 2 inches (51 mm) in width. The baseline can be up to 4 inches (100 mm) wide if so desired.[There are five types of court surface used in professional play. Each surface is different in the speed and height of the bounce of the ball. The same surface plays faster indoors than outdoors.
The players (or teams) start on opposite sides of the net. One player is designated the server, and the opposing player is the receiver. Service alternates game by game between the two players (or teams.) For each point, the server starts behind their baseline, between the center mark and the sideline. The receiver may start anywhere on their side of the net. When the receiver is ready, the server will serve, although the receiver must play to the pace of the server. In a legal service, the ball travels past the net (without touching it) and into the diagonally opposite service box. If the ball hits the net but lands in the service box, this is a let or net service, which is void, and the server gets to retake that serve. The player can serve any number of let services in a point and they are always treated as voids and not as faults. A fault is a serve that falls long or wide of the service box, or does not clear the net. There is also a "foot fault", which occurs when a player's foot touches the baseline or an extension of the center mark before the ball is hit. If the second service is also a fault, the server double faults, and the receiver wins the point. However, if the serve is in, it is considered a legal service. A legal service starts a rally, in which the players alternate hitting the ball across the net. A legal return consists of the player or team hitting the ball before it has bounced twice or hit any fixtures except the net, provided that it still falls in the server's court. A player or team cannot hit the ball twice in a row. The ball must travel past the net and bounce in the other players court. A ball that hits the net during a rally is still considered a legal return. The first player or team to fail to make a legal return loses the point. A tennis match is determined through the best of 3 or 5 sets. Typically for both men's and women's matches, the first player to win two sets wins the match. At certain important tennis tournaments for men, including all four Grand Slam tournaments, Davis Cup and the final of the Olympic Games, the first player to win three sets wins the match. A set consists of games, and games, in turn, consist of points. A game consists of a sequence of points played with the same player serving. A game is won by the first player to have won at least four points in total and at least two points more than the opponent. The running score of each game is described in a manner peculiar to tennis: scores from zero to three points are described as "love", "fifteen", "thirty", and "forty" respectively. (See the main article Tennis score for the origin of these words as used in tennis.) If at least three points have been scored by each player, and the scores are equal, the score is "deuce". If at least three points have been scored by each side and a player has one more point than his opponent, the score of the game is "advantage" for the player in the lead. During informal games, "advantage" can also be called "ad in" or "ad out", depending on whether the serving player or receiving player is ahead, respectively.
