A point in tennis is the smallest subdivision of the match, the completion of which changes the score. A point can consist of a double fault by the server, in which case it is won by the receiver; otherwise, it begins with a legal serve by one side's server to the receiver on the other, and continues until one side fails to make a legal return to the other, losing the point. Four points win a game, counted as 15, 30, 40. A game must be won by at least two points.
Play of a single point
The players stand on opposite sides of the net. One player is designated the server, and the opposing player is the receiver. The players alternate serving from game to game. From point to point within a game, the server alternates between the right and left sides of his end of the court. At the start of each point, the server stands behind his baseline, between the center mark and one of the sidelines. The receiver may stand anywhere on his side of the net, usually behind the diagonally opposite service box, the target for the server's ball. A legal serve is any serve which does not fault. A fault occurs if the ball is touched by anything other than the racket, between the time the server throws the ball into the air to serve it and the time at which it lands in the designated service box; service faults are also incurred for missing the ball, stepping across the baseline before striking the ball, and walking or running while serving. Two consecutive faults result in the opponent winning the point. The receiver must allow the serve to bounce once before returning it, or they lose the point. If the ball touches the net on an otherwise legal serve the serve is retaken, without being counted as a fault. If a legal serve is made, the players then alternate returning the ball from their side of the court to the opponent's. The point is lost by whichever player first:
allows the ball to bounce on the player's own side of the court, and then fails to hit the ball before it bounces again, or
hits the ball, unless either
* the ball subsequently bounces on the first bounce in the opponent's court, or
* the ball is subsequently hit by the opponent, or hits the opponent, before it bounces
intentionally contacts the ball with the racket more than once, without it being hit by the opponent, or
touches the ball with anything other than the racket, or
hits the ball before it has passed over the net to the player's side, or
touches any part of the net with their person, or
hits the ball after their partner has already done so, before the ball has returned to the other side.
The rules allow such actions as:
bouncing the returned ball off any part of the net before it lands in the correct court,
returning of a ball before it has bounced at all on that side,
reaching over the net to hit the ball if it has landed on the player's side and then blown or spun back over the net,
accidentally touching the ball twice with the racket,
returning the ball around a net post, and
returning the ball under the net cord between the net and singles stick.
Because the lines are drawn just inside the courts, the ball is considered "in" if it touches any part of the relevant line. On clay courts the ball leaves an impression in the ground that can be checked; on grass courts a puff of chalk from the line indicates contact from the ball. This is less accurate, however, because dirt from the grass court resembles the chalk and can also be thrown up after being struck with a ball. In an unofficiated game, the players are to give each other the benefit of the doubton line calls. In an officiated game it is the chair umpire or line umpire's duty to call the ball "out." The chair umpire may overrule a line umpire's call.
Instant replay
Computer-assisted video tracking technology has improved to the point that it can determine the position of a ball at impact with a margin of error less than five millimeters. Accordingly, starting with the NASDAQ-100 Open in March 2006, most top-level tournaments allow systems such as Hawk-Eye to be used to settle disputed line calls. Players are allowed to appeal to Hawk-Eye on disputed calls with a limitation: They lose the privilege if the appeal goes against them three times per set, with one more challenge allowed during a tie-breaker. In the 2006 NASDAQ-100 Open, challenges by men were upheld 38% compared to 27% for women. At the Championships, Wimbledon 2008, in the men's singles challenges were successful 29% of the time with an average of 6.6 challenges per match, in the women's singles challenges were successful 20% of the time with an average of 3.8 challenges per match.
As of 1999, in Division I tennis in the NCAA, a let service is considered playable. This rule change was made to prevent receivers from falsely claiming a valid service to be a let, which is a call that cannot be overruled. Thus, a service that hits the net before landing in the service box is a playable shot, and must be returned by the receiver. Otherwise, the receiver loses the point.
During high school tennis team matches, players may have to follow a few different rules:
Pro set: Instead of playing best out of three sets, players may play one pro set. A pro set is first to 8 games instead of 6. All other rules apply.
Super tie-break: This is played sometimes after players split sets. It decides who wins instead of a third set. This is played like a regular tie-break but the winner must attain ten points instead of seven.
Super duper tie-break: Same as Super tie-break, but the winner must attain 12 points instead of ten.
No-ad: The players play through the match without any ads. When the game is at deuce the receiving player has the option to choose what side of court they want to receive the serve for the final game-deciding point. The first player or doubles team to four points wins the game.
