Tennis is a sport played within a defined rectangular zone called the court. The court is divided into two equal portions by a net that runs across the width of the court. Tennis is played between two players (singles) or between two teams each consisting of two players (doubles). The object of the game is to hit the ball over the net into the opposition zone such that the ball is not successfully returned. The player or team that has hit the un-returnable shot scores a point. A game is decided by a set number of points, with a determined number of games constituting a set, and a defined number of winning sets determining the overall winner of the match.

In its present form, tennis originated in France in the sixteenth century. A precursor to the modern game, which used a racquet that was more similar to a squash racquet, was played even earlier. Records date back to the twelfth century.

Once a game restricted to the wealthy and privileged, the appeal of tennis grew in the twenty-first century. Now, municipally operated and maintained tennis courts are a recreational mainstay of most communities. Tennis is a medal sport of the Summer Olympics and the various professional tours are a popular spectator pastime. As with the sport of golf, professional tennis has four tournaments that are considered to be paramount in prestige to the others. Winning one of these tournaments is a career accomplishment. Winning all four of the tournaments in the same competitive season—a feat called the "Grand Slam"—has been accomplished by only a handful of players.

The tennis court can be made of different surfaces, including concrete or wood ("hard court"), grass, or pressed clay. The surface affects the way the game is played. The tennis ball will rebound with greater energy off a hard court, since less energy is absorbed on impact. Conversely, a ball that is hit so that it spins through the air after it leaves the racquet face will tend to move more following impact with clay or grass, whose increased friction grabs the ball more than a hard court. As well, the surface character of concrete will be much more uniform than either grass or clay, whose surfaces can be marred during play. The changing character of the latter surfaces can add to the appeal and challenge of the tennis match.

The set-up of a player for a shot will be different on concrete, where he or she cannot slide into the shot, versus grass or clay, where sliding to meet the ball is the desirable way to achieve the best shot. Players who are successful on the various surfaces must have an ability to alter their style of play to match the conditions.

Of the four Grand Slam tournaments, the United States Open and Australian Open are hard court competitions, the French Open utilizes a clay court, and Wimbleton (an English tournament) is a grass court event.

Whatever the composition of the playing surface, the dimensions of a tennis court are standard. In a singles match, the rectangular surface is 78 ft (almost 24 m) long and 27 ft (slightly over 8 m) wide. For a doubles match, the length of the court is the same, but the width increases to 36 ft (almost 11 m). The different widths are denoted by an outer set of lines running the length of the court and two other lines parallel to these that define the width of the singles area.

Another line runs parallel to the length of the court. This line begins at the center of the court and extends 21 ft (6.4 m) to either side of the net. This line helps create the zones where the first shot of each point (the service) must land.

Horizontal lines are also present. A central line divides the court in half. A mesh-like net with a reinforced top is placed over this line. A rope strung through the top of the net connects the net with support posts at either side of the court. A properly positioned net should be 3 ft 6 in (slightly over 1 m) off the ground at each post and 3 ft (slightly less than 1 m) high at center court. Two other horizontal lines positioned 21 ft (6.4 m) on either side of the net join the central line to complete the service zones (which, if viewed from overhead, look like four smaller rectangles positioned within the main rectangle of the court). Finally, two other horizontal lines (the baselines) define either end of the court.

In singles play, one competitor is on either side of the net. In doubles play, the two teammates are on the same side of the net. Typically, one of the doubles teammates will be closer to the baseline, with the other teammate positioned closer to the net. Play begins in the same way in singles or doubles competition, with the server, who is positioned behind the baseline, hitting the ball to the receiver. Recreational

Tennis has broad appeal as a recreational and competitive sport.
level players may elect to hit the ball with an underhand motion or after tossing the ball slightly up into the air to improve their changes of making contact with the ball. Elite players will toss the ball about 10 ft (3 m) above them, giving time to position their body to make an aggressive movement toward the descending ball in such a way that a great deal of energy from the body movement and swinging of the racquet is transferred to the ball. If properly done, the ball can rocket off the racquet face at over 100 mph (160 kmp).

If the ball does not land in the same rectangular service area on the other side of the net, or does not make it to the net, or hits the net on its way to the other side of the court, the server must hit another shot. If the second shot is unsuccessful, the competitor is awarded the point for that part of the game.

The receivers' task is to make contact with the ball and send it back over the net before or after it has bounced. Only one bounce is allowed. If the ball bounces twice or more before being returned, the server is awarded the point for the play. Sometimes the ball moves so fast that contact is not made. This is called an "ace" and is worth a point to the server. Sometimes the receiver is successful in sending the ball back to the server's side of the court. Play then continues, with the ball being hit back and forth across the net (a rally) until one player is unable to return the ball. Then, the other person or team is awarded the point for that portion of the game.

A complete tennis game is called a match. The match is divided into sets, and each set consists of games. Finally, each game is decided by the number of points accumulated. Each player begin each game with zero points (also called "love"). As serves are won, a player or team accumulates points in the order 15, 30, 40, 41, 42 (game point). One player or team serves for an entire game. The next game, the service shifts to the other player or team.

As one or the other competitor wins games, a point is reached where one player or team has won the predefined number of games necessary to win the set. A new set then begins, with the tally of games won shifting back to zero. A complete match is won when a player or team wins a defined number of sets.

Depending on the experience and athleticism of the competitors, a match can be relatively sedate and relaxing, or a fast-paced and serious contest. Recreational contests typically involve just the players, who govern play and interpret results by themselves. More competitive contests may involve an umpire (who is the ultimate authority should disputes arise and who sits in an elevated seat, permitting a view of the entire court), other umpires who determine if serves and other shots land in bounds or out of bounds, and helpers who retrieve the balls and keep play moving at a brisk pace.

Tennis is played using a specially designed racquet and a ball constructed of rubber that is hollow and is covered by a felt layer. The felt imparts some resistance to the ball, allowing it to be hit so as to give it spin, and so it will not bounce wildly high or wide on impact. Elite players can hit the ball such that it rotates clockwise or counterclockwise while moving through the air, or has a vertically oriented, downward spin (topspin). The different spins will cause the ball to move differently on contact with the court.

In top-flight tennis, the felt is worn out quickly, and a new ball will be put into play after a designated number of games (typically nine) or when both players or teams agree that the ball in play is worn out.

In singles tennis, each player must roam over the entire half of the court to try to return shots that have landed close to the net, far back on the court, or near each sideline. In doubles competition, the teammates will coordinate their movements so that they most efficiently cover the territory of the court. This is important since, in doubles, the play can be very fast, with the ball often cannoning back and forth over the net without touching the ground.

A tennis ball can be hit with a forehand or a backhand motion, and can be returned very close to the net at higher speeds or high up in the air at a slower speed (a lob). The choice of shot depends on the player's ability and the position of the competitor. For example, if a competitor is very close to the net, a prudent shot can be to hit a lob that lands far back in the court, since it may be difficult for the competitor to reach the shot and return it.

Part of the appeal of tennis is that it can be played for a lifetime and by people of all physical abilities. Millions of people around the world are active participants and millions more enjoy the thrill of watching the game.

SEE ALSO Badminton; Racquetball; Squash; Tennis racquet construction.