Four points are needed to win a standard tennis game, provided the player leads by at least two points. Tennis counts points as love, 15, 30, 40, and then game, so a player who wins four points in a row takes the game at 40–love.
The unusual numbering comes from older scoring traditions, although its exact origin is uncertain. Some explanations connect 15, 30, and 40 with positions on a clock face, while others point to historical scoring systems that used quarter-point increments. Whatever its origin, the sequence is now standard in tennis.
The answer changes when the score reaches 40–40, called deuce. From deuce, a player must win two consecutive points: the first creates advantage, and the second wins the game. That is why a game can require more than four points. In a deciding-point or no-ad format, local rules may shorten deuce, but the ordinary scoring system still begins with four points as the minimum winning total.
A common mix-up is confusing points with games. Four points normally win a game, six games usually win a set, and two or three sets—depending on the competition—win a match.