Point (tennis)

The players (or teams) stand on opposite sides of the net. One player is designated the server, and the opposing player (or, in doubles, one of the opposing players) is the receiver. The players (or teams) alternate serving with each game. From point-to-point within a game, the server alternates serving from the right and left sides of their court. The first point of a game is always served from the server's right side. At the start of each point, the server stands behind their baseline, anywhere between the center line and the sideline, and serves the ball at the service box diagonally opposite. The receiver may stand anywhere on their side of the net and prepare to return the serve.

A legal serve is any serve which is not a "fault." A fault occurs if the ball does not land in the appropriate service box on the receiver's side of the net. Service faults are also incurred for missing the ball, stepping on the baseline, center line, or sideline before striking the ball (foot fault), and walking or running while serving. Two consecutive faults (double fault) result in the receiver winning the point. The receiver must allow the serve to bounce once before returning it, or else the server automatically wins the point.

If the ball touches the net during an otherwise legal serve ("let" or "net" service), the serve is retaken without being counted as a fault. After the serve, if the ball touches the net during the point but lands safely on the opposite side, then play continues as normal without stopping.

Once a legal serve is made, the players then alternate returning the ball from their side of the court to the opponent's side. 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 a second time, or
• hits the ball, unless either
  • the ball safely bounces on the first bounce in the opponent's court (although the ball may hit the net before bouncing), or
  • before it bounces, the ball is hit by the opponent, or hits the opponent
• intentionally contacts the ball with the racket more than once, without it being hit by the opponent,^[a] or
• touches the ball with anything other than the racket (or with the racket after it has left the player's hand), or
• hits the ball before it has passed over the net to the player's own side, or
• touches any part of the net with their person before the point is over, or
• (in doubles) hits the ball after their partner has already done so, and before the ball has returned to the opposite side.

The rules specifically allow certain actions, such as:

• bouncing the returned ball off any part of the net, including the net post(s), before it lands in the correct court,
• returning a ball before it has bounced on the player's own side (volley), except when returning a serve in which case the served ball must be allowed to bounce
• reaching over the net to hit a ball only if the ball has already bounced on the player's own side and then moved back over the net,
• unintentionally touching the ball twice with the racket,
• returning the ball around a net post and below the height of the net, and
• returning the ball under the net cord between the net and net post.

The lines are considered part of the court and so a ball is "in" the court if it touches any part of the relevant line, even if a majority of the ball bounces outside of the line. In an officiated match, it is the duty of line umpires to call a ball "out" if it bounces outside of the relevant line(s). The chair umpire may overrule the line umpire if they believe an in or out call is clearly incorrect. On clay courts, ball marks left on the court's surface may be visually inspected by the chair umpire after a disputed call. In unofficiated matches, players are responsible for making their own calls on their respective sides of the court, in which case the ethics of the game requires honesty and a willingness to give one's opponent the benefit of the doubt.

Computer-assisted video tracking technology can determine the precise position of a ball at impact with a margin of error less than five millimeters.^[1][b] Accordingly, starting with the NASDAQ-100 Open in March 2006, most top-level professional tournaments allow systems such as Hawk-Eye to be used to settle disputed line calls. When this technology is in place, players are allowed a maximum of three incorrect challenges per set. If a set reaches six games-all, then each player is awarded one additional challenge for the tiebreak.

The use of instant replay technology remains uncommon on clay courts, where visual inspection of ball marks predominates.

As of 1999, in NCAA tennis in the United States, a let service is not retaken and the point continues without stopping.

• ITF Rules of Tennis
• USTA Friend at Court (identical to ITF rules, with added commentary from USTA and a guidebook for unofficiated games)