Tennis is a racket sport played between two opposing players in singles or two teams of two players in doubles. The basic objective is to hit the ball over the net and into the opponent's court so that the opponent cannot return it successfully before it bounces twice, or so that the opponent commits a rules violation. A legal shot must normally travel over the net and land within the appropriate court boundaries.
Players alternate hitting the ball after each return, with the rally continuing until one player or team wins the point. A point can be won through a successful shot that the opponent cannot return, an opponent's ball landing out, a double bounce, a double fault on serve, or certain other faults. Tennis therefore combines a simple central objective with a detailed system governing serving, court boundaries, scoring, equipment, and player conduct.
The court is divided by a net and marked with different lines that have different meanings depending on whether singles or doubles are being played. The baseline forms the rear boundary of the court, while the singles sidelines define the narrower singles court and the doubles sidelines define the wider doubles court. The service boxes are the two rectangular areas immediately beyond the net and between the centre service line and the appropriate service sideline.
During a service game, the server must stand behind the baseline and serve diagonally into the opposite service box. Once the serve has been legally delivered, subsequent shots may generally land anywhere inside the relevant court. In singles, the inner sidelines are used, whereas in doubles the wider court is used. The net also has prescribed dimensions and must be cleared by a legal shot, although the ball may touch the net in certain circumstances and remain playable.
A tennis point begins with a serve, and the server receives two attempts to make a legal serve. The first serve is normally struck from the right side of the court into the diagonally opposite service box, and the next point begins from the left side, with the server continuing to alternate sides. A serve that lands outside the correct service box, fails to clear the net, or otherwise violates the serving requirements is a fault.
If the first serve is a fault, the server receives a second serve. If the second serve is also a fault, a double fault occurs and the receiver wins the point. The server and receiver must generally remain in their prescribed positions until the ball is struck. After a legal serve, the rally develops through alternating shots, and either player may use different strokes, spins, speeds, angles, heights, and court positions to create an opportunity to win the point.
The ball may normally bounce only once on a player's side before it must be returned. A player may hit the ball before it bounces, which is called a volley, or after a bounce, which is commonly called a groundstroke. A player loses the point if the ball bounces twice on that player's side before it is returned, if the player hits the ball outside the relevant court, if the player hits the net and the ball does not legally continue into the opponent's court, or if another applicable rule is broken.
The ball can touch the net during a rally and still be in play provided it subsequently travels correctly into the opponent's court. A player can also legally hit the ball around the side of the net in unusual circumstances if the ball reaches the opponent's court without passing over the top of the net, although this is uncommon.
Tennis uses a distinctive scoring structure based on points, games and sets. Within an ordinary game, points are traditionally announced as love, 15, 30 and 40, although the underlying progression represents zero, one, two and three points. A player normally needs to win four points and lead by two points to win a game. At 40 40, called deuce, the player must win two consecutive points to take the game.
The first point after deuce creates advantage, and winning the following point wins the game, while losing it returns the score to deuce. Sets are normally won by the first player to win six games while leading by at least two games, although a tiebreak is commonly used when the set reaches six games all. Matches can consist of best of three sets or, in some competitions and formats, best of five sets.
Serving and receiving positions are controlled by specific rules, and players change ends during a set according to the scoring sequence. Changing ends ensures that external conditions such as wind, sun and court characteristics are not permanently concentrated on one player. The precise changeover pattern depends on the number of games played and applicable competition rules. Players also receive limited time between points and at changeovers, and they are expected to play at a reasonable continuous pace.
A player cannot normally deliberately delay play without consequence. Equipment is also regulated, particularly the racket and ball specifications used in organised competition. The racket is used to strike the ball, but a player may not deliberately catch, carry or throw the ball with the racket during a point. The ball must be struck with the racket's strings or frame within the rules governing a legal stroke, and deliberately interfering with the opponent's play can constitute a violation.
Tennis has many rules that distinguish ordinary faults from unusual situations. A let can require a point or service attempt to be replayed, most famously when a served ball touches the net and nevertheless lands in the correct service box. A hindrance can arise when something prevents a player from making a normal stroke, with the ruling depending on whether the interference was deliberate or accidental and whether it came from a player, opponent, official, or outside circumstance.
Players can also be penalised for unsportsmanlike conduct, coaching violations where coaching is prohibited, racket abuse, audible obscenity, deliberate delays, or other breaches of competition regulations. Modern professional tennis also uses electronic systems and review procedures in many competitions to assist officials with line calls and other decisions. The precise technology and review arrangements vary between tournaments, but the fundamental rules remain based on the Laws of Tennis and the regulations of the relevant governing organisation.
The basic rules are therefore best understood as a connected system rather than as isolated instructions. The serve starts every point, the rally determines who wins that point, points accumulate into games, games accumulate into sets, and sets determine the match winner according to the competition format. Court geometry determines whether a ball is in or out, while serving rules determine whether a point begins legally.
The distinction between singles and doubles changes the court boundaries and introduces additional positioning considerations, while the scoring system creates strategic situations such as break points, game points, set points and match points. Rules about lets, tiebreaks, changeovers and conduct ensure that unusual circumstances can be handled consistently. Although the basic concept is simply to get the ball past the opponent and inside the court, tennis requires players to understand serving, returning, rallying, positioning, scoring, boundaries and sportsmanship simultaneously.
