A point in tennis is the smallest subdivision of the match. A point can consist of a double fault by the server, in which case the point is automatically won by the receiver. In all other cases, a point begins when a legal serve is hit by the server to the receiver on the opposite side of the court, and continues until one side fails to legally return the ball to the opposite side. Whichever side fails to do so loses the point and their opponent wins it.
In the advantage scoring system, the first side to win four points by a two-point margin wins the game. To start a game, both sides begin at "love" (zero points). The first point won by a side is called "15," the second point is "30," and the third point is "40." If both sides have won three points in a game (i.e., 40-40), the score is called "deuce." From deuce, whichever side wins the following point is said to have "advantage" and can win the game by winning the next point (two-point margin). If the side with advantage loses the next point, the score returns to deuce, and play continues until one side wins two consecutive points from deuce, thereby winning the game.
Alternatively, if no-advantage (no-ad) scoring is used, then the first side to win four points wins the game, without the requirement of a two-point margin. No-ad scoring means any one game will consist of a maximum of seven points, as opposed to advantage scoring which allows for a hypothetically infinite number of points per game. For this reason, no-ad scoring is used in some competition formats to ensure quicker matches.
During a tiebreak game, each side's points are counted more simply as 0, 1, 2, etc. rather than love, 15, 30, etc. used during other games. A standard tiebreak is won by the first side to win seven points by a two-point margin. Other variations (e.g., 10-point tiebreak) are sometimes used.