Ace: A valid serve that is not reached by the opponent.
Backhand: A stroke in which the player turns so the shoulder of the racket-bearing arm faces the net before bringing the racket forward and across the body to meet the ball.
Baseline: The lines on either end of the court representing the outer limits of the length of the court.
Break: When a game is won by the player receiving serve. To be "up a break" in a set means a player/team has broken the opponent's serve one more time than the player/team has been broken.
Change-over: Time spent between an odd number of games in the match when players prepare to change sides of the court.
Chip-and-charge: To hit a shot with backspin (slice) and follow it into the net. A chipped approach shot bounces less, thus making it harder for the opponent to hit a forceful passing shot.
Deuce: A tie at 40 is called deuce. Because a game must be won by two points, play continues from deuce until one player leads by a margin of two points.
Double fault: If both serve attempts fail. The opponent wins the point.
Drop shot: A lightly hit shot with backspin that drops softly over the net, generally intended to be an out-right winner (if the ball bounces twice before the opponent reaches it).
Foot fault: If the server's foot enters the court before the service is completed. The baseline is part of the court.
Forehand: The player pivots the body so the shoulder of the non-racket-bearing arm faces the net. The player then swings the racket forward to meet the ball.
Half-volley: When a ball is hit just after it bounces. Half-volleys are among the most difficult shots in tennis and are typically hit be a player not in position to volley his or her opponent's shot.
Let: If a served ball touches the net and then land in the proper (diagonally opposite) service box, a let is called and the server is permitted to serve again.
Lob: A high shot struck when the opponent is at the net. A lob can be offensive, if hit with topspin and with the intent of clearing the opponent's head and bouncing away from the retreating player. Lobs are often defensive, struck by a player on the run who needs time to regain position.
Love: Term meaning zero points. The derivation of "love" is either a corruption of l'oeuf (French for "an egg") or playing not seriously, but for the love of the game.
On serve: When neither player/team is up a break (that is, the players/teams are either tied or the serving player/team is down by only one game).
Passing shot: When a player hits a groundstroke in attempt to pass an opponent who has taken position at the net.
Racket: A piece of equipment used to hit the ball. It features a network of tightly-knit strings inside an oval-shaped frame. The racket is held by its lower portion, known as the grip.
Receiver: The player who receives the ball from the server.
Serve: Begins every point of a tennis match; the server is the player who initiates the point.
Serve-and-volley: To follow a serve immediately into the net with the intent of winning the point with a volley or a forced error by the opponent. This is an increasingly rare tactic in modern tennis.
Tie-break: Employed when a set becomes tied at 6 games. A tie-break is generally played to seven points, but because it too must be won by at least two points, it may be extended.
Top spin: When a player strikes the ball so that it spins from low to high as it travels forward. Topspin enables a player to strike the ball with more power -- the added spin helps bring the ball down and keep it in play.
Under spin: Occurs when a player strikes the ball so that it spins from high to low as it travels forward. This shot is called a slice. Under spin causes the ball to lose speed and to bounce lower.
Unforced error: When a player makes a mistake -- hits the ball out or in the net -- deemed to have not been caused by the opponent's shot.
Volley: Occurs when a player hits the ball before it bounces. The volley is most often employed when a player is playing close to the net.
Winner: A shot that the opposing player cannot return, similar to a service ace.