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 (1 point), 30 (2 points), 40 (3 points). A game must be won by at least two points.