In tennis, deuce refers to a tie score of 40 where either player needs to win by two points for the game to conclude. When the score becomes tied at 15 or 30, the score is announced as 15-all or 30-all. However, when the score reaches 40-40, it is called deuce. At this point, one player or team will need to win at least two points in a row to win the game. When the server wins the deuce point, it is called Ad-In, but when they lose the deuce point, it is called Ad-Out. If the team with the advantage (Ad-In or Ad-Out) wins another point, they win the game, or it goes back to deuce. There is no maximum number of deuces that a match can have, and it is possible for every game in a tennis match to go to deuce.